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Mateusz Gładysz

Pathway read-through · Basal cell carcinoma

Basal cell carcinoma: the edge you cannot see

Mateusz Gładysz · MD · FEBOPRAS · FEBHS

A read-through for a New Zealand regional melanoma and high-risk skin cancer MDM, for the registrar preparing a case and the consultant chairing it. The core line carries the decisions; the closed panels carry the groundwork and the divergences.

Clinical content verified References checked 46 questions 7 MDM cases Version 1.1

All cases are constructed for teaching and describe no real patient. Clinical content verified 1 October 2026. Sources: NZSCD SCC and BCC Guidelines – High-Risk Criteria 2023 and Follow-Up Recommendations (May 2023), linked by Skin Cancer NZ · Te Aho o Te Kahu MDM standards (March 2024) · Pharmac Schedule and Hospital Medicines List, October 2026 · Cancer Council Australia KC guideline, NHMRC-approved 2019; MAGICapp v1.4, April 2024 · NCCN Basal Cell Skin Cancer v1.2027 (risk table quoted from v2.2026) · BAD 2021 · EADO 2023.

Not covered: eyelid and orbital BCC beyond routing (BAD 2021 excludes eyelid BCC); reconstruction; management of basosquamous carcinoma beyond recognising it as a cSCC-pathway tumour (the Cancer Council Australia position, followed here); genodermatoses other than Gorlin syndrome and xeroderma pigmentosum. In this read-through, the MDM’s terms of reference accept complex BCC at any site and high-risk cSCC outside the head and neck; head and neck cSCC goes to a separate Head and Neck MDM. Check your own MDM’s terms of reference.

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SchemaThe biopsy gives a subtype; subtype and site predict hidden extension; extension decides margin, margin control or not cutting.
Changes in practice since June 2023
  • 30 June 2023 — RACGP endorsement of the Cancer Council Australia keratinocyte cancer guideline lapsed. The guideline remains NHMRC-approved (7 November 2019).
  • 19 April 2024 — Cancer Council Australia guideline republished on MAGICapp as version 1.4. Recommendations and evidence base are unchanged from 2019.
  • 2026 — NCCN Basal Cell Skin Cancer moved from v1.2026 (2 September 2025) through v2.2026 to v1.2027, now current. The two-tier risk table reproduced here is the v2.2026 version.
  • 11 September 2026 — Pharmac published the November 2026 CTAC agenda, which includes first-line cemiplimab for advanced cutaneous SCC (application P-001628). No BCC indication is included; no systemic therapy for BCC is funded.

WorkupIs the biopsy subtype trustworthy?

Basics: BCC subtypes, biopsy types and what the report should contain

Lower-risk subtypes: nodular, superficial, pigmented, infundibulocystic, fibroepithelial. Higher-risk: , infiltrative, (sclerosing), , sarcomatoid (WHO classification, as reproduced in EADO 20231). Many tumours contain more than one pattern; management follows the worst.

Biopsy: punch and shave sample part of the lesion; excision removes all of it. Cancer Council Australia prefers excision biopsy “when appropriate”, with punch, shave or curettage when complete excision is not possible.

Report: there is no dataset for BCC, but RCPath publishes one (February 2019); the covers excision specimens of head and neck non-melanocytic skin cancer, and excludes superficial BCC. Cancer Council Australia’s minimum items are tumour type, subtype, thickness in the dermis, and perineural, vascular or lymphatic spread, with margins.

Case
GP referral. 52-year-old man, 16 mm pink scaly plaque on the upper back. 3 mm punch from the centre: “superficial BCC”. Examination: a firm, shiny 4 mm papule at the lower pole of the plaque. GP proposes imiquimod.
What is the next step?
□ Guess   □ Fairly sure   □ Certain
✗ (a) Treats one 3 mm core as a map of a 16 mm lesion. The papule is unexplained, and imiquimod is only for superficial BCC.
✓ (b) Correct. Plan from the worst component. A clinical feature the biopsy does not explain is a reason to sample again before a subtype-dependent treatment.
✗ (c) Trunk, under 2 cm, primary: low risk on every list. The problem is sampling, not margin control.
✗ (d) Cryotherapy also depends on a superficial or low-risk diagnosis. The unexplained papule undermines it just as it undermines imiquimod.
A punch samples one small cylinder. Mixed histology is present in 32–43% of BCCs, and in one prospective Mohs series only 5 of 49 mixed tumours (10%) had been reported as mixed on the biopsy. Of 166 failures after imiquimod, 5-FU or PDT for “superficial” BCC, 38.6% were non-superficial subtypes. The papule is the clinical sign of what the core missed.

Rule

A biopsy is a sample. Plan from the worst component reported, and when the lesion contains something the biopsy does not explain (a papule within a plaque, ulceration, an ill-defined or scarred area), re-biopsy or excise before choosing a treatment that depends on the subtype. Biopsy is expected before any non-surgical treatment, and strongly advised before surgery that removes part of the nose, eyelid, lip or ear.

A tumour’s management should be based on the worst part of its histopathology… An insufficient biopsy may not represent all tumour types in a lesion with a mixed pattern.

Source: Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024, biopsy section; PP 9.5.1 (excision biopsy when appropriate); PP 15.1.1 (biopsy before imiquimod). NZSCD SCC and BCC Guidelines – High-Risk Criteria 20233: incisional biopsy “where a biopsy result may change clinical management”.

Rule

Before planning, check that the report names every pattern present, the margins, and perineural invasion with nerve calibre and depth. If is reported without detail, ask the pathologist before deciding. Cancer Council Australia asks that basosquamous or metatypical carcinoma be managed as cSCC; BAD 2021 and NCCN classify basosquamous carcinoma as a high-risk BCC subtype, and NZSCD is silent. This read-through follows Cancer Council Australia: such a report moves the tumour to the cSCC pathway.

Tumour type; degree of differentiation or subtype of the tumour; tumour thickness in the dermis; perineural, vascular or lymphatic spread.

Source: Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024, pathology minimum dataset; PP 11.5.1 (discuss reported PNI with the pathologist); terminology table (basosquamous and metatypical “should be considered to be forms of cSCC”). NCCN (v3.2024 wording): report PNI if the nerve lies below the dermis or measures ≥0.1 mm. No ICCR dataset4 exists for BCC; RCPath publishes a BCC dataset5 (February 2019). The RCPA structured reporting protocol covers excision specimens of head and neck non-melanocytic skin cancer; superficial BCC is excluded (Gupta R et al., Pathology 2023;55:743–596).

Nodular BCClow-risk histologyMicronodular BCChigh-risk histology
Clinical and dermoscopic appearancePearly papule, arborising vesselsOften indistinguishable from nodular
Where the difference is foundThe histology reportThe histology report
Risk class (NZSCD, NCCN, CCA)Low if site, size and borders are lowHigh on every list
Standard excision margin4 mm (NCCN, BAD); NZSCD 4–6 mmAt least 5 mm (BAD), or margin control
Curettage and cauteryAn option under 2 cm at a low-risk siteNot appropriate
Check
Curettage and cautery was planned for a 9 mm BCC of the upper back reported as nodular. An addendum reclassifies it as micronodular. What should change?
□ Guess   □ Fairly sure   □ Certain
✓ (a) Correct. Micronodular is not low-risk histology, so non-surgical treatment is not appropriate, and the low-risk 4 mm figure does not apply.
✗ (b) More cycles do not address a subtype that sits outside the indication for curettage.
✗ (c) Imiquimod is for superficial BCC. Micronodular is further from that indication than nodular.
✗ (d) Subtype is a risk feature in its own right. Under NCCN and BAD one high-risk feature makes the tumour high risk; NZSCD lists its criteria without stating a count.
Worked case — 5 steps
Referral70-year-old woman, 9 mm well-defined pearly papule on the left forearm. Punch biopsy: “BCC with nodular and micronodular patterns”. Primary lesion. Immunocompetent.
  1. WorkupReport sufficient: both patterns are named. The worst component governs: plan as micronodular.CCA pathology
  2. StagingHigh risk by subtype alone. Site (forearm), size (under 2 cm) and borders are low risk; under NCCN one high-risk feature is enough, and micronodular histology is on the NZSCD list.NZSCD; NCCN
  3. TreatmentNo curettage, cryotherapy or topical treatment. Non-surgical treatment is for low-risk histology in favourable sites.CCA EBR 11.3.2
  4. TreatmentExcise with at least 5 mm, including fat at the base; orient the specimen. BAD high-risk margin; NZSCD 4–6 mm at its upper end.BAD 2021; NZSCD
  5. Follow-upNZSCD schedule: 6–12-monthly for 5 years, then at least annually for life. Applies after any BCC.NZSCD Follow-Up 2023
What would change this? A report of “nodular” alone would make the same lesion low risk: a 4 mm margin, and curettage would become an option.

Why?

Why do biopsy errors in BCC tend to under-call the subtype rather than over-call it?

Show answer
A sample can only show the patterns present in it. Mixed tumours are common (32–43%), and a punch or shave captures a small fraction of the lesion, so any pattern outside the sample is absent from the report. Errors therefore run towards omission of a component, usually the one that matters. Lim’s 22% biopsy-to-Mohs subtype drift is the measured size of that error; the final subtype is decided on the whole specimen.
Evidence and other guidelinesCCA: basosquamous = cSCC

How often the biopsy misleads. Mixed histology 32.4–43% across three series; in Cohen’s prospective Mohs series (2006)7 only 5 of 49 mixed tumours (10%) had been reported as mixed on biopsy; Lim 20228 (n = 1,686) found 22% subtype drift between index biopsy and final . Cancer Council Australia cites a shave-versus-punch comparison (Russell 19999) but prefers neither.

Basosquamous. Cancer Council Australia: basosquamous and metatypical tumours are “more likely to recur”, are “less than 5% of all BCCs”, “generally behave more like cSCC and, in practice, they should be considered to be forms of cSCC”; it asks pathologists to avoid the terms and lists “metatypical” among poor-prognosis subtypes (PP 12.2.2). NCCN lists basosquamous among aggressive subtypes (v3.2024 wording), and BAD 202110 lists basosquamous differentiation among the high-risk features of BCC: both keep it within BCC. NZSCD 2023 does not list it. This read-through follows Cancer Council Australia.

Terminology. Cancer Council Australia prefers “fibrosing” to “desmoplasia”, to avoid confusion with desmoplastic melanoma.

Data quality. Cancer Council Australia: “the quality of data supporting all the observed associations between morphological and histological subtype and prognosis is poor.” The subtype framework is the best available, not a validated one.

Datasets. There is no ICCR dataset for cSCC or BCC; ICCR’s published skin datasets cover invasive melanoma and Merkel cell carcinoma. RCPath publishes datasets for both, BCC5 and cSCC11 (February 2019). The RCPA structured protocol covers head and neck excision specimens (superficial BCC excluded).

StagingWhich features make it high risk, and who decides “complex”?

Basics: why BCC has risk lists instead of a stage

BCC almost never metastasises: published rates run from 0.0028% to 0.55%, and the upper bound cannot be traced to a primary source. The harm is local: recurrence, and the tissue lost to repeated surgery. So BCC is classified by risk of local recurrence, using a checklist of features rather than a TNM stage.

Three lists matter here. NZSCD 2023 (New Zealand Skin Cancer Doctors Society, linked by Skin Cancer NZ). NCCN, two tiers, where any one high-risk feature makes the tumour high risk. Cancer Council Australia, which has no table but defines the facial . “High risk” changes the margin and the technique. “Complex” is a separate word, set by each MDM’s terms of reference rather than by national guidance: it decides whether the case comes to this MDM.

Case
Four primary, well-defined, biopsy-proven BCCs in immunocompetent patients. Classify each against NZSCD 2023 and the NCCN table.
□ Guess   □ Fairly sure   □ Certain
NCCN only. NCCN makes the whole head and neck high risk at any size; the NZSCD mask area is ears, temples, eyes, nose and lips, and the cheek is not in it.
Both. Over 2 cm on the trunk is high risk on NZSCD (>2 cm) and NCCN (≥2 cm).
NZSCD only. NZSCD lists age under 25; NCCN does not.
Neither. Trunk, under 2 cm, nodular, primary, well-defined.
The two lists disagree on site and on age. NCCN makes any head and neck BCC high risk; NZSCD names the mask area only. NZSCD adds age under 25 and Gorlin syndrome, which NCCN omits. Under NZ priority the NZSCD sheet decides; record where NCCN differs, because it changes whether margin control is recommended.

Rule

FeatureNZSCD 2023NCCN (v2.2026 table)
SiteMask area (ears, temples, eyes, nose, lips), genitals, hands, feetHead, neck, hands, feet, pretibial, anogenital: any size
Size>2 cm, or tetheredTrunk or extremities ≥2 cm
SubtypeMicronodular, infiltrative, sclerosing, morphoeiformAggressive growth pattern
Borders; recurrence; immunosuppression; PNIAll high riskAll high risk
Depth beyond subcutaneous tissueHigh riskNot listed
Prior radiotherapy siteNot listedHigh risk
Age under 25; Gorlin syndromeHigh riskNot listed

NCCN and BAD treat one high-risk feature as enough; NZSCD lists its criteria without stating a count, and this read-through applies the same one-feature reading. Under NZ priority use the NZSCD list, and record an NCCN-only feature, since it changes the margin-control recommendation.

Location in the ‘mask’ or ‘H’ area of the face (ears, temples, eyes, nose, and lips), genitals, hands, or feet.

Source: NZSCD SCC and BCC Guidelines – High-Risk Criteria 20233 (verbatim criteria). NCCN Basal Cell Skin Cancer v1.2027 (risk table as printed in v2.2026); the v1.2027 table wording has not been confirmed. Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024: H-zone definition.

Rule

High risk is not the same as complex. Te Aho o Te Kahu excludes simple BCC from cancer MDMs and leaves the criteria to each MDM’s terms of reference; no national definition of “complex BCC” was found. One possible operational definition, used for the questions in this read-through and not a published one: complex means any of (a) a Cancer Council Australia PP 12.2.2 trigger: bone invasion, rapid growth, recurrence, inadequate margins where further surgery is problematic, , lymphovascular or in-transit spread, nodal disease, or , infiltrative or metatypical subtype; (b) persistent or recurrent T3/T4 BCC; (c) difficult-to-treat or locally advanced disease, or systemic therapy under consideration; (d) carcinoma; (e) or age under 25; (f) a transplant recipient or CLL with multiple keratinocyte cancers.

Simple non-melanoma skin cancers (SCC/BCC) are excluded.

Source: Te Aho o Te Kahu, Standards for high-quality cancer MDMs in Aotearoa NZ12 (March 2024), Quality Area 4. Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024: PP 12.2.2; CBR 12.2.1.

Worked case — 5 steps
Referral81-year-old woman, 22 mm morphoeic BCC of the left temple, recurrent 3 years after excision; clinically ill-defined. Not immunosuppressed.
  1. StagingHigh risk on every list. Recurrent, temple (mask area), over 2 cm, morphoeic, ill-defined.NZSCD; NCCN
  2. WorkupComplex: this MDM. Recurrence and a poor-prognosis subtype are Cancer Council Australia PP 12.2.2 triggers.Example definition (a)
  3. TreatmentMargin-controlled excision is the first question. Recurrent facial BCC: “wide surgical excision or Mohs”; Mohs showed significantly fewer recurrences here.CCA EBR 11.3.1
  4. TreatmentRadiotherapy if further surgery would be problematic or margins are inadequate. PP 12.2.2 lists recurrence and inadequate margins for consideration of postoperative radiotherapy.CCA PP 12.2.2
  5. Follow-up6–12-monthly for 5 years, then at least annually for life. Late recurrences occur: in Maastricht, 14% of recurrences after treatment of recurrent facial BCC appeared after year 5.NZSCD Follow-Up 2023
What would change this? A primary, well-defined 9 mm nodular BCC at the same site is high risk (mask area) but not complex: dermatology or plastics treat it without the MDM.

Why?

Why does BCC use a risk checklist rather than a TNM stage to plan treatment?

Show answer
Because the outcome that matters is local recurrence, not metastasis, which occurs in at most about 0.5% of cases. TNM stages extent to predict spread and survival. The decisions in BCC (margin, margin control, whether a non-surgical treatment will work) depend on how far the tumour extends beyond what is visible, which subtype, borders, site, recurrence and nerve involvement predict better than size alone.
Evidence and other guidelinesNZSCD ≠ NCCN on site and age

Where the lists disagree, with consequence. A 12 mm nodular BCC of the cheek is high risk under NCCN (head and neck, any size), so NCCN directs it to Mohs or ; it is outside the NZSCD and the Cancer Council Australia H-zone, so NZ practice allows standard excision. The same applies to forehead and scalp. NZSCD adds age under 25, Gorlin syndrome and depth beyond subcutaneous tissue; it omits basosquamous and prior radiotherapy.

Cancer Council Australia has no BCC risk table. Its text: “There is an increased risk of local recurrence for large, deep or ulcerated tumours, especially if incompletely or narrowly excised, and for tumours of micronodular, infiltrating, sclerosing () or superficial multifocal subtype.”

BAD 202110 keeps an area H/M/L site scheme. EADO 20231 uses easy- versus difficult-to-treat.

Metastasis. 0.0028–0.55%; the upper figure has no traceable primary source.

“Complex”. No national keratinocyte-cancer MDM criteria were found; Te Aho o Te Kahu leaves criteria to each MDM’s terms of reference. The example definition above is derived from Cancer Council Australia, EADO and NZSCD for teaching; it is not a published standard.

TreatmentHow far does it extend, and what margin?

Basics: clinical margin, pathological margin and subclinical extension

The clinical margin is measured on the skin, from the visible (ideally dermoscopic) border, before excision. The pathological margin is what the pathologist measures after excision and fixation, and is always smaller. Guideline margins are clinical.

BCC often extends beyond what is visible: subclinical extension. Breuninger’s three-dimensional histology of 2,016 tumours showed that the extension takes the form of narrow finger-like outgrowths, and that it varies with subtype. The is usually clear if a thin layer of subcutaneous fat is taken, because most tumours do not extend beyond the dermis.

Case
Two patients, both excised with a 5 mm clinical margin. P: 8 mm well-defined nodular BCC of the forearm. Q: 15 mm primary morphoeic BCC of the forehead.
On Breuninger’s data, roughly what proportion of each type of specimen will have a positive margin?
□ Guess   □ Fairly sure   □ Certain
✗ (a) Lower than any 5 mm figure in Breuninger’s data, and it keeps the two tumours close together, which they are not.
✗ (b) Applies the small-tumour figure to a morphoeic 10–20 mm tumour: a rule transferred to a subtype it was not derived from.
✓ (c) Correct. Any subtype ≤10 mm: 5% positive at 5 mm. Primary morphoeic 10–20 mm: 18% positive at 5 mm.
✗ (d) Those are the 3 mm figures for the same two groups.
Subtype, not the millimetre, sets the clearance rate. At 5 mm a small BCC is clear in about 95% of specimens; a 10–20 mm morphoeic primary is still positive in 18%, about one in five. Recurrent tumours had significantly more positive margins than primaries (p = .001). The 4–5 mm rule comes from well-demarcated tumours under 2 cm and does not transfer to ill-defined morphoeic disease.

Rule

GuidelineLow riskHigh risk
NZSCD 20234–6 mm clinical margins, wider if ; consider margin control on the head and neck
NCCN4 mmNo figure given: Mohs or PDEMA
BAD 20214 mmAt least 5 mm; deep margin to a clear plane including fat
EADO 20233–4 mm5–15 mm where micrographic surgery is unavailable
Cancer Council AustraliaNo millimetre recommendation; background text cites 4 mm for most nodular BCC

Under NZ priority: 4–6 mm for low-risk BCC, at least 5 mm and often more for high-risk histology, and a thin layer of fat at the base. For morphoeic, infiltrative, recurrent or ill-defined tumours, a clinical margin cannot be relied on: use margin control, or accept that about one in five will still be positive at 5 mm.

Surgery with 4–6 mm clinical margins (or wider if morphoeic type).

Source: NZSCD SCC and BCC Guidelines – High-Risk Criteria 20233. NCCN low-risk 4 mm; high risk: “it is not feasible to recommend a defined margin for standard excision of high-risk BCC” (v3.2024 wording). BAD 202110; EADO 20231 (worked example: a 2 cm tumour with further high-risk features needs “at least 13 mm”). Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024, surgical margins background.

Rule

The 4 mm figure has one source and one population: previously untreated, well-demarcated BCC under 2 cm. Use it there. For other tumours, quote Breuninger: any subtype ≤10 mm, 30%, 16% and 5% positive at 2, 3 and 5 mm; primary morphoeic 10–20 mm, 48%, 34% and 18%.

For tumors with a diameter less than 2 cm, a minimum margin of 4 mm was necessary to totally eradicate the tumor in more than 95% of cases.

Source: Wolf DJ, Zitelli JA. Arch Dermatol 1987;123:340–413 (117 previously untreated, well-demarcated BCC). Breuninger H, Dietz K. J Dermatol Surg Oncol 1991;17:574–814 (n = 2,016, three-dimensional histology).

Slope chart from Breuninger and Dietz, 2,016 basal cell carcinomas examined by three-dimensional histology. Percentage of specimens with a positive margin at clinical margins of 2, 3 and 5 mm. Any subtype, 10 mm or smaller: 30%, 16% and 5%. Primary morphoeic (fibrosing) tumours of 10 to 20 mm: 48%, 34% and 18%. Both lines fall as the margin widens, but the morphoeic line stays higher throughout: at 5 mm it is still slightly above the small-tumour value at 3 mm. Positive margin, % of specimens 0%25%50% 2 mm3 mm5 mm Clinical margin 48%34%18% 30%16%5% Morphoeic, primary,10–20 mm (dashed) Any subtype,≤10 mm (solid) Positive margin, % of specimens 0% 25% 50% 2 mm 3 mm 5 mm Clinical margin 48% 34% 18% 30% 16% 5% Morphoeic, primary, 10–20 mm (dashed) Any subtype, ≤10 mm (solid)
At 5 mm, a 10–20 mm morphoeic primary is about as likely to be incompletely excised as a small BCC taken at 3 mm.
Worked case — 5 steps
Referral74-year-old man, 16 mm primary infiltrative BCC of the upper back, ill-defined on dermoscopy. General surgery has listed excision with a 4 mm margin.
  1. StagingHigh risk: infiltrative subtype and ill-defined borders. Site and size (trunk, under 2 cm) are not what makes it high risk.NZSCD; NCCN
  2. Treatment4 mm is the wrong figure. It was derived from well-demarcated tumours under 2 cm.Wolf & Zitelli 1987
  3. TreatmentPlan at least 5 mm, measured from the dermoscopic border, with fat at the base. BAD high-risk margin; NZSCD 4–6 mm at the upper end or wider.BAD 2021; NZSCD
  4. WorkupOrient the specimen and ask for margin distances. A positive margin can then be located for re-excision.
  5. TreatmentIf a margin is involved: re-excise. High-risk histology.CCA EBR 11.6.2
What would change this? A well-defined nodular BCC of the same size and site would be low risk, and 4 mm would be appropriate.

Why?

Why does the same 5 mm margin clear 95% of small BCCs but only about 82% of 10–20 mm morphoeic primaries?

Show answer
Because the margin is measured from the visible border, and clearance depends on how far the tumour extends beyond it. Morphoeic BCC grows as thin strands in a fibrous stroma that cannot be seen or felt, so its true extent lies further, and less predictably, beyond the visible edge. The same millimetres therefore capture less of the tumour.
Evidence and other guidelinesNCCN gives no high-risk figure; EADO 5–15 mm

Divergence. NCCN declines to give a margin for standard excision of high-risk BCC and directs to Mohs or ; BAD gives at least 5 mm; EADO gives 5–15 mm where micrographic surgery is unavailable, with the worked figure of “at least 13 mm” for a 2 cm tumour with further high-risk features. EADO is the most explicit that a high-risk BCC can need a margin two to three times the low-risk figure.

Cancer Council Australia makes no millimetre recommendation. Background text: “a 4mm margin is required for most nodular BCCs and well-differentiated cSCCs to ensure complete histologic clearance” and “While a margin of 4mm may excise most tumours, it may be excessive in some and insufficient in others.” On the deep margin: “Fear of damaging underlying anatomy and inexperience may cause incomplete deep margins.”

What the evidence is. No randomised trial of margin width exists. Wolf and Zitelli (1987) supports only the 4 mm, >95%, well-demarcated, <2 cm statement; other percentages attributed to it in circulation are not in the published abstract. Breuninger (1991) is the larger dataset and the one that separates subtypes; recurrent tumours had more positive margins than primaries (p = .001).

TreatmentMargin or margin control?

Basics: what Mohs and PDEMA are

Mohs surgery removes the tumour in layers; each layer is mapped and sectioned en face, so the entire peripheral and is examined, and further layers are taken only where tumour is seen. PDEMA (peripheral and deep margin assessment) is the umbrella term: Mohs, staged excision with en face margin sections (“slow Mohs”), and three-dimensional histology. Standard excision is usually examined by vertical sections, which sample the margin at intervals.

In New Zealand the public Mohs service listed is at Te Toka Tumai Auckland; private Mohs services exist elsewhere.

Case
One public Mohs slot is available. X: 70-year-old, primary 11 mm well-defined nodular BCC of the nasal tip. Y: 64-year-old, 10 mm BCC of the nasal sidewall, recurrent 4 years after excision.
On the randomised evidence, which patient has the stronger case for the slot?
□ Guess   □ Fairly sure   □ Certain
✓ (a) Correct. Recurrent facial BCC: 5-year 2.4% vs 12.1% (p = 0.015); 10-year 3.9% vs 13.5% (p = 0.023).
✗ (b) The Maastricht trials randomised primary and recurrent facial BCC to Mohs or standard excision.
✗ (c) Tissue sparing is a legitimate criterion (CCA PP 11.8.1), but it applies to both; the recurrence evidence separates them.
✗ (d) It did not. Primary facial BCC: 5-year 2.5% vs 4.1% (p = 0.397); 10-year 4.4% vs 12.2% (p = 0.100).
The Maastricht programme randomised both groups. Recurrent facial BCC: 5-year recurrence 2.4% with Mohs vs 12.1% with excision (p = 0.015); 10-year 3.9% vs 13.5% (p = 0.023). Primary facial BCC: 5-year 2.5% vs 4.1% (p = 0.397); 10-year 4.4% vs 12.2% (p = 0.100). Only the recurrent comparison reached significance, which is how Cancer Council Australia reads it.

Rule

Where margin control is scarce, prioritise recurrent facial BCC, then the Cancer Council Australia criteria: ill-defined border, aggressive subtype, residual tumour after previous treatment, , facial tumours over 10 mm, and cases where a smaller defect is of clinical value. NZSCD asks for margin control to be considered for high-risk or complex head and neck tumours. The public Mohs service listed is in Auckland; access from other regions varies, so check your region’s referral route. Where Mohs is not available, staged excision with en face margins is the alternative. NCCN accepts as equivalent, and standard excision with vertical sections only where neither is available.

Poorly defined clinical border; infiltrating, micronodular, sclerosing, and other aggressive histological subtypes; residual following previous treatment; located in the H‐zone of the face; large >10mm in diameter on the face.

Source: Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024, PP 11.8.1 (circumstances in which Mohs may be considered; the list ends with defect-size reduction of clinical value); EBR 11.3.1 (recurrent facial BCC: “wide surgical excision or Mohs”). NZSCD SCC and BCC Guidelines – High-Risk Criteria 20233. NCCN advanced algorithm (v2.2026 as reproduced).

Rule

Involved margin. Decide case by case. A positive margin does not mean persistent tumour or inevitable recurrence, so observation is reasonable for a low-risk BCC at a low-risk site after discussion. With high-risk features or a high-risk site, re-excise, with margin control where available. Consider postoperative radiotherapy when further surgery is problematic, and for perineural invasion; discuss reported with the pathologist.

Incompletely excised basal cell carcinomas that have high-risk features, or occur in high-risk anatomical sites, should be re-excised, where possible.

Source: Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024, EBR 11.6.1 and 11.6.2 (Grade C); PP 12.2.2 (postoperative radiotherapy or additional treatment); PP 11.5.1; PP 12.1.1 (postoperative radiotherapy within 6 weeks; practice point).

Two views from above of the same basal cell carcinoma. The visible tumour is an oval with three finger-like outgrowths; the longest runs upward past the dashed clinical margin. Left: bread-loaf processing cuts the specimen into vertical slices a few millimetres apart. The long outgrowth lies between two slice planes, so no slice shows tumour at the margin and the report reads clear while tumour is left behind. Right: complete en face assessment examines the whole peripheral margin as one ring. The same outgrowth crosses the ring and is found. En face methods include Mohs surgery, staged excision with en face sections and three-dimensional histology, grouped as PDEMA. Bread-loaf sections visible tumour clinicalmargin Outgrowth between two planes:report reads clear, tumour left Complete en face margin visible tumour found at the margin whole ringexamined Mohs, staged excision with en facesections, 3-D histology (PDEMA) Bread-loaf sections visible tumour clinical margin Outgrowth between two planes: report reads clear, tumour left Complete en face margin visible tumour found at the margin whole ring examined Mohs, staged excision with en face sections, 3-D histology (PDEMA)
A report can only describe the part of the margin it was shown.
Worked case — 5 steps
Referral77-year-old man, 13 mm primary BCC of the left nasal ala. Punch biopsy: infiltrative. Fit; on warfarin.
  1. StagingHigh risk: mask area and infiltrative subtype. Cancer Council Australia Mohs criteria met: H-zone, aggressive subtype, over 10 mm on the face.NZSCD; CCA PP 11.8.1
  2. TreatmentMargin-controlled surgery is the recommendation. NZSCD: consider margin control for high-risk head and neck tumours.NZSCD
  3. FundingRequest the Auckland public Mohs service if a referral route exists; if not, staged excision with en face margins. Access from other regions varies; check your region’s referral route.
  4. TreatmentIf only vertical sections are available, orient the specimen and plan re-excision for any involved margin. NCCN fallback; high-risk site.CCA EBR 11.6.2
  5. Follow-up6–12-monthly for 5 years, then at least annually for life. In Maastricht, 56% of recurrences of primary facial BCC appeared after year 5.NZSCD; van Loo 2014
What would change this? Recurrence after previous treatment would move this from “may be considered” to the group in which Mohs has shown significantly fewer recurrences.

Why?

Why does complete en face margin assessment find tumour that bread-loaf sections miss?

Show answer
Bread-loaf sections are vertical slices a few millimetres apart, so they examine the margin only where each slice meets it. BCC extends as narrow finger-like outgrowths; one lying between two slices can reach the margin without appearing in any section. En face sections examine the whole peripheral and deep margin surface, so an outgrowth that crosses it is seen wherever it lies.
Evidence and other guidelinesNCCN ≠ CCA on primary facial BCC

The trials. Maastricht (Mosterd, Lancet Oncol 200815; van Loo, Eur J Cancer 201416). Primary facial high-risk BCC: 5-year recurrence standard excision 4.1% (7) vs Mohs 2.5% (4), p = 0.397; 10-year Mohs 4.4% vs excision 12.2%, p = 0.100; 127 of 397 primary tumours were lost to follow-up. Recurrent facial BCC: 5-year Mohs 2.4% vs excision 12.1%, p = 0.015; 10-year 3.9% vs 13.5%, p = 0.023. For primary tumours both arms used 3 mm margins, to standardise the two techniques (as described in Cochrane 2020). Cochrane 202017: Mohs vs excision for high-risk facial BCC at 5 years 3.2% vs 5.2%, RR 0.61 (0.18–2.04), low certainty; no analysable cosmetic data. The claim that Mohs improves cosmesis is not supported by these trials.

Guidelines. NCCN calls Mohs the primary surgical technique of choice for high-risk BCC. Cancer Council Australia: “MMS and wide excision achieve similar cure rates for primary BCC of the face” and “MMS has a statistically significant advantage for high risk recurrent facial BCC, but not for primary at this stage”. BAD: “consider” for primary, “offer” for recurrent. The disagreement is real, not a version lag.

Consequence in NZ. With public Mohs listed only in Auckland, the Cancer Council Australia reading supports treating a primary, well-defined facial BCC locally, and reserving Mohs for recurrent, aggressive-subtype or ill-defined tumours.

Perineural invasion. Cancer Council Australia recommends discussing reported PNI with the pathologist and lists PNI of major or minor nerves among the indications to consider postoperative radiotherapy; NCCN asks for PNI to be reported by calibre (≥0.1 mm) and depth.

TreatmentNot cutting: which option, and how does each fail?

Basics: the non-surgical treatments and what each needs

Curettage and cautery (Cancer Council Australia: EDC) scrapes out soft tumour; it needs training and a curettable tumour. Cryotherapy freezes the lesion and a margin in repeated freeze–thaw cycles. Imiquimod 5% and fluorouracil 5% are creams applied by the patient over weeks. MAL-PDT activates a topical photosensitiser with light. Radiotherapy is given in fractions by radiation oncology.

All except radiotherapy are for small, low-risk BCC. Imiquimod and 5-FU are for superficial BCC; MAL-PDT is used for superficial BCC and, in European guidance, low-risk nodular BCC (EADO 20231), with higher recurrence than excision (Cochrane 202017). None provides a specimen, so clinical clearance is not histological clearance, and the only histology is the biopsy taken beforehand.

Case
66-year-old man, biopsy-proven superficial BCC, 14 mm, left shoulder. Wants to avoid surgery. Asks which non-surgical option is most likely to leave him tumour-free at 5 years.
In the three-arm randomised trial, which option had the best 5-year tumour-free survival?
□ Guess   □ Fairly sure   □ Certain
✗ (a) Lowest of the three: 62.7% at 5 years. Also hospital-only in NZ (RS1127).
✓ (b) Correct. 80.5% (74.0–85.6); hazard ratio vs MAL-PDT 0.48, vs 5-FU 0.65 (P = 0.04). Funded without Special Authority.
✗ (c) Second: 70.0% at 5 years. Funded without Special Authority.
✗ (d) The curves separated: imiquimod was significantly better than both.
Jansen 2018 (n = 601, superficial BCC): 5-year tumour-free survival imiquimod 80.5%, 5-FU 70.0%, MAL-PDT 62.7%. Even the best cream falls short of excision: in SINS (nodular and superficial BCC at low-risk sites), 5-year recurrence was 17.5% with imiquimod and 2.3% with excision. The choice trades recurrence against cosmesis and surgery, and it is valid only if the lesion is truly superficial.

Rule

OptionForHow it failsNZ funding
Curettage and cauterySuperficial or nodular BCC <2 cm, low-risk sitesMorphoeic tumour is not curettable; in fat the curette cannot discriminate; terminal-hair sites (follicular extension)Procedure
CryotherapyBiopsy-proven superficial BCC <2 cm; 3–5 mm margin, repeated cyclesLate recurrence; low-risk histology onlyProcedure
Imiquimod 5%Biopsy-proven superficial BCC; tumour and 5 mm marginUnder-sampled nodular componentYes, no SA
Fluorouracil 5%Superficial BCCAs imiquimod; lower 5-year clearanceYes, no SA
MAL-PDTSuperficial BCC; low-risk nodular BCC in European guidance (EADO 2023)Lowest 5-year clearance of the threeHML, RS1127

Every option in the table depends on the biopsy being right, and none produces a specimen to check it.

Both surgical and nonsurgical treatment modalities can be considered for superficial and nodular basal cell carcinomas in favourable sites.

Source: Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024, EBR 11.1.1 and 11.3.2 (Grade C); EDC, cryotherapy and imiquimod sections; PP 13.1.1 (long-term follow-up after cryotherapy); PP 15.1.1 (biopsy before imiquimod); Quick reference guide18 (2019). NCCN: terminal-hair exclusion for curettage.

Rule

Radiotherapy is the non-surgical option for tumours outside that table: when surgery is declined or inappropriate, and for persistent or recurrent larger tumours after a radiation oncology opinion. It is contraindicated in and xeroderma pigmentosum. Persistence after radiotherapy means biopsy and salvage surgery.

Radiotherapy using curative doses can be considered as an alternative to surgical excision in the definitive treatment of basal cell carcinoma if surgery is either declined by the patient or surgery is inappropriate.

Source: Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024, EBR 12.2.1 (Grade D); CBR 12.2.1 (T3/T4 persistent or recurrent BCC: radiation oncology opinion); PP 12.2.1 (salvage surgery). BAD 202110; NCCN: radiotherapy contraindicated in genetic conditions predisposing to skin cancer.

Worked case — 5 steps
Referral57-year-old woman, 10 mm superficial BCC of the lower back on a 3 mm punch, treated with imiquimod by her GP. Five months after finishing, a firm pink papule has appeared in the treated area.
  1. WorkupTreat as failure until shown otherwise: biopsy the papule. Clinical clearance was not histological clearance.
  2. WorkupExpect a non-superficial subtype. Of 166 failures after imiquimod, 5-FU or MAL-PDT, 38.6% were non-superficial: under-sampling, not transformation.van Delft 2019
  3. TreatmentExcise, with the margin set by the new subtype. A second topical course repeats the error if the tumour is nodular or infiltrative.
  4. Follow-upReview 3–6 months after stopping a topical, and planned follow-up for up to 3 years. This review would have found the papule earlier.NZSCD; CCA PP 19.1.1
  5. FundingImiquimod is funded without Special Authority, and without a biopsy requirement. The biopsy rule is clinical, not a funding rule.
What would change this? Had the original punch shown a nodular component, imiquimod would not have been used: nodular BCC goes to excision or curettage.

Why?

Why does curettage lose its selectivity once the curette reaches subcutaneous fat?

Show answer
Curettage works because BCC is softer than the dermis around it: the curette removes tumour and stops at firm collagen. Fat is softer than tumour, so in fat the curette no longer distinguishes the two and the tactile end point is lost. Morphoeic BCC fails for the opposite reason: its fibrous stroma is not curettable.
Evidence and other guidelinesCCA silent on 5-FU for BCC

Topicals and PDT. Jansen 201819 (J Invest Dermatol; n = 601): 5-year tumour-free survival imiquimod 80.5% (74.0–85.6), 5-FU 70.0% (62.9–76.0), 62.7% (55.3–69.2); imiquimod vs MAL-PDT HR 0.48; imiquimod vs 5-FU HR 0.65, P = 0.04. Cochrane 202017, imiquimod vs excision (SINS20; nodular and superficial BCC at low-risk sites): recurrence 16.4% vs 1.6% at 3 years (RR 10.30) and 17.5% vs 2.3% at 5 years (RR 7.73), moderate certainty; observer-rated cosmesis better with imiquimod (60.6% vs 35.6%, low certainty).

Cross-Tasman. 5-FU is TGA-approved for Bowen’s disease, not BCC, so Cancer Council Australia is silent on it; NZ funds it without restriction. Imiquimod is TGA-approved “for biopsy-proven superficial BCC where surgery is considered inappropriate”, and the PBS requires a biopsy; the NZ Schedule does not.

Curettage and cryotherapy. Kuijpers 200721 (n = 100, non-aggressive head and neck BCC): 5-year recurrence curettage plus cryotherapy 19.6% vs excision 8.4%, p = .10, HR 2.57 (0.79–8.34): not statistically significant. Cancer Council Australia: late recurrences after cryotherapy make long-term follow-up essential.

Radiotherapy. Cochrane: radiotherapy vs excision (with frozen sections) on the face, 4-year recurrence 6.4% vs 0.6%, low certainty.

Old tables. Many modality recurrence tables in circulation go back to Rowe’s 1989 reviews of series published since the 1940s (primary BCC22; recurrent BCC23): weighted averages of published series, not randomised comparisons.

Supply. MAL is listed on the as “any brand” without a pharmacode; whether it is currently supplied in NZ is unconfirmed.

FundingAdvanced BCC in New Zealand: what is funded?

FundingPosition as at the October 2026 Pharmac Schedule and Hospital Medicines List, checked 1 October 2026. Funding and Special Authority criteria change often: check the current Schedule before acting on them.

Basics: registration, funding, and the drugs involved

Medsafe registration allows a medicine to be sold; Pharmac listing makes it publicly funded. They are separate decisions. Hedgehog inhibitors (vismodegib, sonidegib) are oral drugs that block the pathway active in almost all BCC; adverse effects such as muscle spasms, taste loss and hair loss often limit how long they are taken, and tumours can regrow after stopping. Cemiplimab is an anti-PD-1 antibody with activity in BCC after failure or intolerance.

“Locally advanced BCC” has no agreed definition. EADO calls it “a vague term” and uses difficult-to-treat instead: technically difficult sites (eyes, nose, lips, ears), ill-defined or multiply recurrent tumours, previous radiotherapy, patient reluctance and comorbidity.

Case
84-year-old man, 7 cm ulcerated infiltrative BCC of the right temple and upper cheek. Surgery would need orbital exenteration; he declines. ECOG 1. His family ask about “the tablet for skin cancer”.
What is publicly funded for him in New Zealand?
□ Guess   □ Fairly sure   □ Certain
✗ (a) Medsafe approved sonidegib in 2020, but it is not on the Schedule or the HML and is not known to be marketed in New Zealand.
✗ (b) Medsafe-approved for this situation, but not on the Schedule; there is no Special Authority to apply for.
✓ (c) Correct. Surgery and radiotherapy are the only funded treatments for advanced BCC.
✗ (d) Registered for cSCC only and funded for nothing. The November 2026 application is for first-line advanced cSCC.
Registration and funding are different decisions. Vismodegib has Medsafe approval for exactly this situation, laBCC where surgery or radiotherapy is not appropriate, yet is not listed. Sonidegib was approved by Medsafe in 2020 but is not listed and is not known to be marketed in New Zealand. Cemiplimab is registered for cSCC only and funded for nothing. For advanced BCC, systemic therapy in NZ means self-funding or a trial.

Rule

Advanced BCC is an MDM decision, and the first question is whether surgery or radiotherapy can still control it, because those are the funded treatments. Locoregional metastasis: offer surgery or radiotherapy and look for distant disease. Distant metastasis: medical oncology for hedgehog inhibitor consideration. Sequencing choices that foreclose surgery or radiotherapy, such as prolonged delay, foreclose the only funded options.

Patients with locoregional metastases of basal cell carcinoma should be offered surgical excision or radiotherapy if possible. It is appropriate to check for the presence of distant metastatic disease.

Source: Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024, PP 18.1.1; PP 18.1.2 (distant metastatic BCC: medical oncologist or MDT “for consideration of hedgehog signalling pathway inhibitor treatment”); CBR 12.2.1. NCCN advanced BCC algorithm (v2.2026 as reproduced).

Rule

No systemic therapy for BCC is funded. Vismodegib: Medsafe-approved, not listed; Pharmac declined an inactive application for vismodegib in on 8 March 2022. Sonidegib: Medsafe-approved (Prescriber Update, March 2020), not listed on the Schedule or HML, and not known to be marketed in New Zealand. Cemiplimab: registered for cSCC only, funded for nothing; its November 2026 CTAC application is for cSCC. Record the options discussed, that they are unfunded, and the route chosen (trial, self-funding or no systemic therapy).

Adult patients with metastatic basal cell carcinoma, or with locally advanced basal cell carcinoma where surgery and/or radiation therapy are not appropriate.

Source: Medsafe datasheet, Erivedge (vismodegib)24, revised 12 August 2022 (indication). Medsafe Prescriber Update 41(1), March 202025 (Odomzo (sonidegib) 200 mg capsules, basal cell carcinoma, among recent approvals of new active ingredients). Pharmac Schedule26 and HML27, October 2026; Pharmac decision 8 March 202228; CTAC November 2026 agenda29 (published 11 September 2026). See the funding table.

Worked case — 5 steps
Referral79-year-old woman, 6 cm infiltrative BCC of the left cheek and lower eyelid, 3 years’ growth. No palpable nodes. ECOG 1. Declines exenteration.
  1. StagingLocally advanced by MDM judgement: there is no agreed definition. Difficult to treat: eyelid site, size, and a patient who declines the operation.EADO 2023
  2. TreatmentRadiation oncology opinion for definitive radiotherapy. Surgery declined: radiotherapy is the funded alternative. Confirm there is no Gorlin syndrome or xeroderma pigmentosum.CCA EBR 12.2.1
  3. FundingVismodegib: registered for this indication, not funded. Discuss self-funding only if radiotherapy is declined or unsuitable.
  4. TreatmentIf a hedgehog inhibitor is used, it is not a lifelong plan. Adverse effects limit duration; tumours can regrow after stopping.
  5. Follow-upRecord the options, the funding status and her decision. The MDM record is the evidence that the unfunded options were offered.
What would change this? A palpable node would make this locoregional metastatic BCC: surgery or radiotherapy to the basin, and a search for distant disease (CCA PP 18.1.1).
Evidence and other guidelinesMedsafe approves; Pharmac does not fund

Hedgehog inhibitors. ERIVANCE final analysis (Sekulic, BMC Cancer 201730): vismodegib investigator-assessed response 60.3%, mBCC 48.5%; median duration 26.2 and 14.8 months; median overall survival in mBCC 33.4 months. BOLT 42-month analysis (Dummer, Br J Dermatol 202031): sonidegib 200 mg, central-review response laBCC 56% (43–68%), mBCC 8%. The vismodegib figure is investigator-assessed and so the more favourable measure; there is no head-to-head trial.

After a hedgehog inhibitor. Cemiplimab in laBCC (Stratigos, Lancet Oncol 202132): independent-review response 31% (21–42%), complete response 6%, grade 3–4 treatment-emergent adverse events 48%.

NCCN advanced algorithm (v2.2026, as reproduced): laBCC → surgery (consider neoadjuvant systemic therapy; Mohs or ; standard excision with vertical sections if neither is available) or radiotherapy; systemic therapy only if surgery and radiotherapy are not feasible. Nodal disease → surgery ± adjuvant radiotherapy. Metastatic → systemic therapy, with radiotherapy or surgery for limited disease. The neoadjuvant hedgehog inhibitor option has no funded equivalent in NZ.

Access. No Pharmac consultation on vismodegib is open. Whether a supplier compassionate-access programme for cemiplimab operates in NZ is unconfirmed.

WorkupThe young patient with many BCCs

Basics: Gorlin syndrome in brief

Gorlin syndrome (basal cell naevus syndrome) is autosomal dominant, caused by variants in PTCH1 or, less often, SUFU, genes that normally restrain the hedgehog pathway. Features include multiple BCCs from a young age, jaw (odontogenic) keratocysts, palmar and plantar pits, falx calcification, and a risk of medulloblastoma in childhood. A BCC before age 20 is a major criterion in the Kimonis criteria; the Evans criteria use age 30, and there is no single agreed set. Some cases arise without a family history.

Xeroderma pigmentosum is a recessive DNA-repair disorder with skin cancers from childhood. Both conditions make radiotherapy harmful.

Case
27-year-old man, fifth BCC since his first at age 18 (back, scalp, nose). Now a 9 mm nodular BCC of the nasal tip; radiotherapy is booked for next month to avoid a nasal scar. Outdoor worker.
What should the MDM recommend?
□ Guess   □ Fairly sure   □ Certain
✗ (a) Radiotherapy in Gorlin syndrome can produce large numbers of new BCCs in the field. A first BCC at 18 must be explained first.
✓ (b) Correct. A BCC before 20 is a major criterion in the Kimonis criteria (before 30 in the Evans criteria). Surgery is funded and safe whatever the result.
✗ (c) Genetic confirmation takes time; the harm of irradiating a Gorlin patient cannot be undone, and surgery is available now.
✗ (d) A 9 mm nodular BCC of the nasal tip is high risk (mask area) and should be excised; PDT is for superficial or low-risk nodular BCC.
A first BCC at 18 meets a major criterion for Gorlin syndrome in both the Kimonis (before 20) and the Evans (before 30) criteria, whatever the sun history. GeneReviews lists radiotherapy among the agents to avoid if there are alternative treatments, and BCCs can then arise in the irradiated field. NCCN treats radiotherapy as contraindicated in every genetic condition predisposing to skin cancer, and BAD names Gorlin syndrome and xeroderma pigmentosum. The irreversible step is the one to stop.

Rule

Ask every patient the age at their first BCC. A BCC before 20 (before 30 in the Evans criteria), several BCCs in a young adult, jaw keratocysts or palmar pits: assess for and refer to genetics before any radiotherapy. NZSCD classes age under 25 and Gorlin syndrome as high risk. Once suspected: no radiotherapy; surgery for nodular and aggressive tumours; for biopsy-proven superficial ones, funded topicals or MAL-PDT, both supported by guidance although the evidence in the syndrome is limited. Hedgehog inhibitors are unfunded (the Gorlin application was declined in 2022) and not lifelong.

Agents/circumstances to avoid: Radiotherapy if there are alternative treatments, especially in childhood.

Source: GeneReviews, Nevoid basal cell carcinoma syndrome33 (chapter summary, “Agents/circumstances to avoid”). NCCN: radiotherapy contraindicated for genetic conditions predisposing to skin cancer. BAD 202110 (Gorlin syndrome and xeroderma pigmentosum). NZSCD SCC and BCC Guidelines – High-Risk Criteria 20233. Pharmac decision 8 March 202228. BCNS guideline 202234 (Verkouteren, Br J Dermatol): topical treatments as alternatives to repeated excision. MAL-PDT consensus in Gorlin syndrome 201435 (Basset-Seguin, J Eur Acad Dermatol Venereol).

PTCH1 variantcommonerSUFU variantless common
Medulloblastoma risk1.7% (2 of 115 carriers)Up to 20 times higher
Brain MRI, birth to age 5NoYes
Jaw keratocyst screeningFrom age 2; annual OPG from about 8Not indicated
Dermatology examination startsAge 10Age 20
RadiotherapyContraindicatedContraindicated
Brain MRI for meningioma; pelvic ultrasound for ovarian fibromaYesYes
Check
A 3-year-old has Gorlin syndrome with a SUFU variant. Which surveillance item does she need that a PTCH1 carrier of the same age does not?
□ Guess   □ Fairly sure   □ Certain
✓ (a) Correct. SIOPE 2021: brain MRI in early childhood for SUFU carriers only.
✗ (b) That is the PTCH1 start age; SUFU carriers start at 20.
✗ (c) Recommended for both genotypes.
✗ (d) Jaw keratocyst screening is for PTCH1 carriers only; none occurred in the reported SUFU families.
Worked case — 5 steps
Referral38-year-old woman, known PTCH1 Gorlin syndrome, 14 BCCs to date. Six new lesions: four biopsy-proven superficial BCCs on the back, a 7 mm nodular BCC of the cheek and an 8 mm infiltrative BCC of the nasal ala.
  1. WorkupComplex: this MDM. Gorlin syndrome.Example definition (e)
  2. TreatmentNo radiotherapy at any site. Contraindicated in Gorlin syndrome.BAD; NCCN
  3. TreatmentBack: imiquimod or 5-FU; cheek: excision 4–6 mm; nasal ala: margin control. Funded topicals for biopsy-proven superficial BCC; mask area and infiltrative subtype for the ala.NZSCD; CCA PP 11.8.1
  4. FundingVismodegib is not funded; Pharmac declined the Gorlin application in 2022. If self-funded, it is a period of treatment, not a lifelong plan.
  5. Follow-upLifelong skin surveillance, and the PTCH1 schedule for other organs. SIOPE 2021
What would change this? A SUFU variant would remove jaw screening from her relatives’ schedules and add early brain MRI for affected children.

Why?

Why is radiotherapy harmful in Gorlin syndrome when it is a standard BCC treatment in others?

Show answer
Every cell in a Gorlin patient already carries one inactivated copy of a hedgehog-pathway restraining gene. A BCC needs the second copy lost too. Radiation damages the second copy in many cells across the whole field at once, so irradiated skin can go on to produce large numbers of new BCCs. In sporadic BCC both hits must happen in the same cell, so the field is not similarly primed.
Evidence and other guidelinesPharmac declined vismodegib for Gorlin (2022)

Genotype. Smith 201436 (J Clin Oncol): medulloblastoma in 2 of 115 carriers (1.7%); each of three families had one case, a risk “up to 20× higher”; no odontogenic keratocysts in the SUFU families.

Criteria. There is no single agreed set. The Kimonis criteria, revised at the 2011 BCNS colloquium (Bree), make a BCC before age 20, or multiple BCCs, a major criterion; the BCNS guideline (Verkouteren, Br J Dermatol 202234) reproduces that version, and SIOPE also uses age 20. The Evans criteria, as used in Manchester, set the age at 30 (Jones, J Skin Cancer 201137).

Topicals and PDT. The BCNS guideline keeps surgical excision as the standard and calls noninvasive topical treatments useful alternatives, because repeated excision leaves many scars. A 2014 expert consensus on MAL-PDT in Gorlin syndrome (Basset-Seguin, J Eur Acad Dermatol Venereol35), drawing on 83 treated patients and nine published reports, considered it effective for superficial BCC of any size, with better results in nodular BCC under 2 mm thick. The evidence is limited and rests largely on expert consensus.

Surveillance. SIOPE Host Genome Working Group 2021 (Guerrini-Rousseau, Fam Cancer38): dermatology examination from age 10 (PTCH1) or 20 (SUFU); keratocyst screening from age 2 with annual OPG from about 8 for PTCH1 only; brain MRI from birth to 5 years for SUFU only; brain MRI for meningioma and pelvic ultrasound for ovarian fibroma for both; prolonged and thorough follow-up after radiotherapy, with skin examination starting earlier.

Divergence. NZSCD makes age under 25 and Gorlin syndrome high-risk features; the NCCN table lists neither, so an NCCN-only reading can miss the syndrome in a young patient with a small trunk BCC.

Funding. Pharmac declined an inactive application for vismodegib in Gorlin syndrome on 8 March 2022. No systemic therapy for BCC is funded.

Xeroderma pigmentosum. BAD includes it in the radiotherapy prohibition; it is not addressed in the Cancer Council Australia recommendations.

Follow-upWho needs follow-up, and for how long?

Basics: what BCC follow-up is for

Follow-up after BCC looks for two things: new keratinocyte cancers elsewhere, which is most of the yield, and local recurrence at the treated site. A visit is a full skin examination with the scar and, after a non-surgical treatment, the treated area. Patients are taught to examine their own skin. Much of this can be done in primary care; NZSCD is the New Zealand society for doctors who do it.

Case
70-year-old man, third BCC in 5 years. Four years ago a primary 12 mm infiltrative BCC of the nasal ala was excised with clear margins; no recurrence. The clinic proposes discharge at 5 years with no further skin checks.
What should the MDM advise?
□ Guess   □ Fairly sure   □ Certain
✗ (a) Clear margins lower the risk of local recurrence; they do nothing for new primaries.
✗ (b) No guideline sets 3-monthly lifelong review for BCC; it uses clinic capacity without evidence.
✗ (c) Not for facial BCC: 56% of recurrences of primary high-risk facial BCC in the Maastricht trial appeared after year 5.
✓ (d) Correct. NZSCD: 6–12-monthly for 5 years, then at least annually for life. After a non-first skin cancer, 82.0% had another within 5 years.
Two figures argue against stopping at 5 years. In the Maastricht trial 56% of recurrences of primary high-risk facial BCC appeared after year 5, and after a non-first keratinocyte cancer 82.0% of patients had another within 5 years. NZSCD asks for at least annual review for life. The review can move to primary care; it should not stop.

Rule

SourceAfter BCC
NZSCD 20236–12-monthly for 5 years, then at least annually for life; review 3–6 months after stopping a topical for superficial BCC
Cancer Council AustraliaAnnual skin examination as a minimum after any keratinocyte cancer; planned follow-up up to 3 years after non-surgical treatment without histological clearance
BAD 2021No routine follow-up for an isolated, adequately treated BCC
EADO 20233–12-monthly by risk

Under NZ priority, follow NZSCD. The number of previous keratinocyte cancers predicts new ones better than the features of the last tumour. For facial and high-risk BCC, do not stop at 5 years.

BCC: 6–12 monthly for the first five years, and then at least annually for life. 3–6 months after cessation of topical treatment of superficial BCC.

Source: NZSCD SCC and BCC Guidelines – Follow-Up Recommendations39, May 2023. Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024, PP 19.1.1; Quick reference guide18 (“There are no standard evidence-based protocols for surveillance after KCs”). BAD 202110. EADO 20231.

Rule

Chemoprevention is for patients with multiple keratinocyte cancers. Nicotinamide is unfunded and bought over the counter; its BCC-specific effect was not significant. Acitretin is funded under SA2024. Sun protection remains advice for every patient.

May be a useful chemopreventive adjunct … in high risk, immune-competent individuals with a history of multiple keratinocyte cancers. It should not be recommended for lower-risk individuals.

Source: Cancer Council Australia KC guideline2, NHMRC-approved 2019; MAGICapp v1.4, April 2024, nicotinamide key point (predates ONTRANS). ONTRAC: Chen AC et al., NEJM 2015;373:1618–2640. Pharmac Schedule26, October 2026 (acitretin SA2024; nicotinamide not listed).

Worked case — 5 steps
Referral58-year-old woman, 12 mm superficial BCC of the left thigh treated with imiquimod; finished 4 months ago; clinically clear. First skin cancer. Immunocompetent.
  1. Follow-upReview now: 3–6 months after stopping the cream. Clinical clearance is not histological clearance.NZSCD Follow-Up 2023
  2. Follow-upPlanned follow-up of the treated site for up to 3 years. Non-surgical treatment without histological clearance.CCA PP 19.1.1
  3. Follow-upThen 6–12-monthly skin checks to 5 years, then at least annually, in primary care. NZSCD
  4. Follow-upTeach self-examination; advise sun protection. Sunscreen reduced SCC in the Nambour trial; it did not reduce BCC.
  5. FundingNicotinamide not indicated. Single keratinocyte cancer: Cancer Council Australia advises against it for lower-risk patients.
What would change this? A papule in the treated area at review would mean a biopsy, not reassurance: 38.6% of failures after topical treatment were non-superficial subtypes.

Why?

Why does the number of previous keratinocyte cancers predict new ones better than the features of the last tumour?

Show answer
New primaries arise from the whole sun-damaged field, not from the treated tumour. Each previous cancer marks accumulated field damage and susceptibility, so the count measures the field; the features of one excised tumour describe only its own risk of local recurrence. Wehner’s cohort: 40.7% developed another keratinocyte cancer within 5 years after a first, 82.0% after a non-first.
Evidence and other guidelinesNZSCD lifelong ≠ BAD none

Divergence. NZSCD (mirroring NCCN) follows every BCC for life; BAD does not routinely follow an isolated, adequately treated BCC; Cancer Council Australia sets an annual skin examination as the minimum and says “there are no standard evidence-based protocols for surveillance after KCs”; EADO 3–12-monthly by risk. For the solitary low-risk BCC, the NZ position is the most intensive of the four.

Risk of another cancer. Wehner 201541 (JAMA Dermatol): after a first keratinocyte cancer, a new one in 14.5% at 1 year, 31.1% at 3 years, 40.7% at 5 years; after a non-first, 43.9%, 71.1% and 82.0%. The cohort excluded basal cell naevus syndrome and immunocompromised patients. NZSCD cites 30–50% for another BCC and a four-fold increase in melanoma diagnosis after a keratinocyte cancer.

Late recurrence. van Loo 201416: 56% of recurrences of primary and 14% of recurrent facial BCC appeared after 5 years. Cryotherapy recurrences can be late (CCA PP 13.1.1).

Prevention. ONTRAC (n = 386; 500 mg twice daily for 12 months): keratinocyte cancers −23% (95% CI 4–38), P = 0.02; BCC −20% (−6 to 39), P = 0.12; SCC −30%, P = 0.05; no benefit after stopping. ONTRANS (Allen, NEJM 202342) in transplant recipients: 207 vs 210 cancers, rate ratio 1.0 (0.8–1.3), P = 0.96; stopped early for poor recruitment (n = 158), so underpowered. Nambour sunscreen trial43: no effect on BCC (rate ratio 1.03, 0.73–1.46).

FundingNZ funding position at October 2026 Schedule (verified 1 October 2026)

FundingPosition as at the October 2026 Pharmac Schedule and Hospital Medicines List, checked 1 October 2026. Funding and Special Authority criteria change often: check the current Schedule before acting on them.

The single reference for every funding statement in this document. No systemic therapy for advanced or metastatic BCC is publicly funded in New Zealand.

SettingAgentFunded?Conditions
Superficial BCC, topicalImiquimod 5% creamYesFully subsidised; no Special Authority, no restriction. Biopsy before use is a clinical rule, not a funding rule.
Superficial BCC, topicalFluorouracil 5% creamYesFully subsidised; no Special Authority, no restriction.
Superficial BCC, PDTMethyl aminolevulinate 16% creamHospital onlyHML, restriction RS1127: dermatologist or plastic surgeon, or an endorsed Health NZ hospital protocol. Not in the community Schedule. Supply in NZ unconfirmed.
Advanced or metastatic BCCVismodegibNoMedsafe-approved for metastatic BCC, and laBCC where surgery and/or radiotherapy are not appropriate. Not listed. Inactive application for Gorlin syndrome declined 8 March 2022.
Advanced or metastatic BCCSonidegibNoMedsafe approval for BCC (Odomzo 200 mg capsules; Prescriber Update, March 2020); current consent status not confirmed. Not listed on the Schedule or HML; not known to be marketed in New Zealand.
BCC after a hedgehog inhibitorCemiplimabNoMedsafe provisional consent for cSCC only; BCC use is off-label. Not listed for any indication. Application P-001628 (first-line advanced cSCC) is on the November 2026 CTAC agenda.
Chemoprevention, multiple keratinocyte cancersAcitretinYesSpecial Authority SA2024: dermatologist, vocationally registered GP or nurse practitioner; pregnancy exclusion and counselling; no indication restriction.
Chemoprevention, multiple keratinocyte cancersNicotinamideNoNot subsidised; over-the-counter purchase.
Definitive or postoperative treatmentRadiotherapyYes (public)Health NZ radiation oncology. Contraindicated in Gorlin syndrome and xeroderma pigmentosum.
Margin-controlled surgeryMohs surgeryAuckland public serviceListed by Te Toka Tumai Auckland public dermatology. Access from other regions varies; check your region’s referral route. Private services exist. Staged excision with en face margins is the alternative where Mohs is not available.

Sources: Pharmac Pharmaceutical Schedule26 (September 2026 PDF; October 2026 online) and Hospital Medicines List27 (RS1127; SA2024); Pharmac decision 8 March 202228 (inactive applications declined); CTAC November 2026 agenda29 (published 11 September 2026). Medsafe datasheets: Erivedge24 (revised 12 August 2022), Libtayo44 (revised 2 October 2025). Medsafe Prescriber Update 41(1), March 202025 (sonidegib approval).

MDM listSeven referrals, in the order they arrive

Each step reveals the next. The final step asks for the two-sentence directive.

Case 1 · GP referral, shin — no subtype

Referral74-year-old woman. 14 mm ulcerated lesion, right shin. Shave biopsy: “basal cell carcinoma”; no subtype; margins not commented on. GP asks whether 5-FU cream is suitable. Type 2 diabetes; slow healing.
Step 1
What is needed before a treatment is chosen?
□ Guess   □ Fairly sure   □ Certain
✓ (a) Correct. The treatment choice depends on it (CCA pathology dataset).
✗ (b) Depth is a histological question here; imaging does not supply a subtype.
✗ (c) Pretibial skin is high risk under NCCN, but the first gap is the subtype.
✗ (d) A cream is only for superficial BCC, and the subtype has not been reported.

Case 2 · “Complex BCC” with a parotid mass

Referral67-year-old man. 18 mm ulcerated lesion, left temple. Incisional biopsy: “basosquamous carcinoma”. Examination: firm 15 mm left pre-auricular (parotid) mass. Referred to this MDM as “complex BCC”.
Step 1
Which pathway and forum apply?
□ Guess   □ Fairly sure   □ Certain
✗ (a) Treats a probable nodal metastasis as a margin problem.
✗ (b) The node is the evidence that this tumour behaves differently.
✗ (c) Cancer Council Australia: basosquamous “should be considered to be forms of cSCC”. The BCC pathway would under-treat the node.
✓ (d) Correct. This read-through follows Cancer Council Australia in managing basosquamous carcinoma as cSCC (BAD and NCCN treat it as a high-risk BCC subtype). Under its routing assumption, head and neck cSCC goes to the Head and Neck MDM, not this one, and there is a probable nodal metastasis.

Case 3 · The tablet, and what is funded

Referral86-year-old woman. 7 cm ulcerated infiltrative BCC of the right scalp and forehead, 5 years’ growth. CT: erosion of the outer table, no intracranial extension. No palpable nodes. ECOG 2. Declines major reconstruction. Her daughter asks about “the tablet”.
Step 1
What is the first recommendation?
□ Guess   □ Fairly sure   □ Certain
✓ (a) Correct. CCA EBR 12.2.1: radiotherapy when surgery is declined or inappropriate.
✗ (b) Palliation alone is an option she may choose, but not the first recommendation for a fit-enough patient.
✗ (c) Registered for cSCC only and funded for nothing.
✗ (d) Skips the funded option. Radiotherapy is the alternative when surgery is declined.

Case 4 · PNI “present”, no detail

Referral71-year-old man. 11 mm BCC, left nasal ala, excised by his GP with 3 mm margins. Report: “infiltrative BCC; perineural invasion present; deep margin involved.” Nerve calibre and depth not stated. Immunocompetent.
Step 1
What is needed before the plan is finalised?
□ Guess   □ Fairly sure   □ Certain
✗ (a) Imaging is for large-nerve or clinical PNI; the report has not said which this is.
✗ (b) Premature: the margin is involved and the PNI is uncharacterised.
✗ (c) Re-excision is needed, but the PNI detail decides whether radiotherapy or nerve imaging follows.
✓ (d) Correct. CCA PP 11.5.1; NCCN reports PNI by calibre (≥0.1 mm) and depth.

Case 5 · Referred “for a follow-up plan”

Referral61-year-old man. 8 mm nodular BCC, right flank, excised with a 4 mm margin: nodular; margins clear (closest 2 mm); no PNI. First skin cancer. Immunocompetent. Referred to the MDM “for a follow-up plan”.
Step 1
Does this case need MDM discussion?
□ Guess   □ Fairly sure   □ Certain
✓ (a) Correct. Primary, small, trunk, nodular, clear margins.
✗ (b) A 4 mm clinical margin yields a smaller pathological margin; 2 mm clear is a clear margin.
✗ (c) Follow-up for simple BCC is set by the treating clinician.
✗ (d) This MDM takes complex BCC only, and Te Aho o Te Kahu excludes simple BCC from MDMs.

Case 6 · Radiotherapy first, Gorlin later

Referral26-year-old woman. Sixth BCC; first excised at 17. A nasal BCC was treated with radiotherapy 3 years ago elsewhere. Now three new BCCs within the radiotherapy field and two on the back. Jaw cyst removed at 15.
Step 1
What is the priority?
□ Guess   □ Fairly sure   □ Certain
✗ (a) Further radiotherapy compounds the problem.
✗ (b) The field lesions need a diagnosis first, PDT suits only biopsy-proven superficial BCC, and the priority is the syndrome.
✗ (c) A BCC at 17 and a jaw cyst are two Gorlin features, and the irradiated field is already producing tumours.
✓ (d) Correct. Radiotherapy is contraindicated once the syndrome is suspected.

Case 7 · Primary facial BCC, one Mohs service

Referral70-year-old woman. 12 mm well-defined nodular BCC, left nasal sidewall; punch biopsy nodular only. Primary. Fit. Plastic surgery can excise with 5 mm margins and a local flap within 4 weeks. Public Mohs: Auckland; a referral route from her region is not confirmed.
Step 1
Which NZSCD feature makes this BCC high risk?
□ Guess   □ Fairly sure   □ Certain
✗ (a) Nodular is low-risk histology on every list.
✗ (b) Only age under 25 is an NZSCD feature.
✗ (c) The NZSCD size threshold is over 2 cm. Over 10 mm on the face is a Cancer Council Australia Mohs criterion.
✓ (d) Correct. The nose is in the NZSCD mask area.

NumbersThresholds that change a decision

Number
Low-risk BCC: standard excision margin under NCCN and BAD: ___ mm
mm
□ Guess   □ Fairly sure   □ Certain
4 mm. From previously untreated, well-demarcated BCC under 2 cm (Wolf & Zitelli: >95% cleared). Decides whether a standard margin is enough.
Number
BAD high-risk BCC: peripheral margin of at least ___ mm
mm
□ Guess   □ Fairly sure   □ Certain
At least 5 mm (BAD 2021). NCCN gives no figure and directs to Mohs or PDEMA.
Number
Primary morphoeic BCC 10–20 mm excised with a 5 mm margin: positive in about ___ % of specimens
%
□ Guess   □ Fairly sure   □ Certain
18% (Breuninger). The reason a clinical margin is not relied on for morphoeic BCC.
Number
NCCN: a BCC of the trunk or extremities becomes high risk at a diameter of ___ cm
cm
□ Guess   □ Fairly sure   □ Certain
2 cm (≥2 cm NCCN; >2 cm NZSCD). Changes the margin and, under NCCN, the technique.
Number
NCCN asks for perineural invasion to be reported if the involved nerve measures at least ___ mm
mm
□ Guess   □ Fairly sure   □ Certain
0.1 mm, or any nerve below the dermis. Calibre decides whether radiotherapy and imaging are discussed.
Number
Kimonis criteria: a BCC before age ___ is a major criterion for Gorlin syndrome
years
□ Guess   □ Fairly sure   □ Certain
20 (Kimonis criteria; the Evans criteria use 30). A BCC this early triggers assessment for Gorlin syndrome and stops radiotherapy until it is excluded.
Number
Cancer Council Australia: after non-surgical treatment without histological clearance, planned follow-up for up to ___ years
years
□ Guess   □ Fairly sure   □ Certain
3 years (PP 19.1.1).
Number
Imiquimod is applied to the tumour and a margin of ___ mm
mm
□ Guess   □ Fairly sure   □ Certain
5 mm (Cancer Council Australia). Treating the visible lesion alone under-treats it.
Number
NZSCD: 6–12-monthly follow-up after BCC for the first ___ years, then at least annually for life
years
□ Guess   □ Fairly sure   □ Certain
5 years, then annual for life.
Number
Curettage and cautery or cryotherapy (Cancer Council Australia quick reference): BCC under ___ cm
cm
□ Guess   □ Fairly sure   □ Certain
2 cm, at low-risk sites.
Number
After a non-first keratinocyte cancer, ___ % had another within 5 years (Wehner)
%
□ Guess   □ Fairly sure   □ Certain
82.0%. Decides lifelong review for patients with multiple prior cancers.

Your answersCounts only

Answer key

GlossaryTerms used in this document

Gorlin syndrome
Basal cell naevus syndrome. Autosomal dominant; PTCH1 or SUFU variants. Multiple early BCCs; radiotherapy contraindicated.
H-zone
CCA: central face, eyelids, eyebrows, periorbital, nose, lips, chin, mandible, pre- and postauricular skin and sulci, temple and ear.
HML
Hospital Medicines List (Section H of the Pharmac Schedule): medicines funded for use in Health NZ hospitals.
ICCR
International Collaboration on Cancer Reporting. Its skin datasets cover invasive melanoma and Merkel cell carcinoma; there is none for cSCC or BCC.
MAL-PDT
Photodynamic therapy with methyl aminolevulinate 16% cream and red light. For superficial BCC and, in European guidance, low-risk nodular BCC; hospital-only funding in NZ.
Mohs stage
One layer excised, mapped and examined en face during Mohs surgery. Further stages are taken only where tumour is seen.
PDEMA
Peripheral and deep en face margin assessment: complete margin examination, including Mohs, staged excision with en face sections and 3-D histology.
PNI
Perineural invasion. Report calibre (≥0.1 mm or not), depth (dermal or deeper) and whether a named nerve is involved.
PTCH1
Commonest Gorlin gene. Jaw keratocysts; medulloblastoma risk 1.7% (2 of 115) in one series.
RCPA protocol
Royal College of Pathologists of Australasia structured reporting protocol. It covers excision specimens of head and neck non-melanocytic skin cancer; superficial BCC is excluded. There is no ICCR dataset for BCC.
RS1127
HML restriction on methyl aminolevulinate cream: prescribed or recommended by a dermatologist or plastic surgeon, or under an endorsed Health NZ hospital protocol.
SUFU
Less common Gorlin gene. Medulloblastoma risk up to 20 times that of PTCH1; no jaw keratocysts in reported families.
Special Authority
Pharmac’s criteria-based funding approval for a named medicine and indication. No BCC systemic therapy has one.
basosquamous
Tumour with BCC and squamous features (also “metatypical”). Cancer Council Australia: should be considered a form of cSCC. BAD and NCCN: a high-risk BCC subtype.
bread-loaf
Conventional vertical slicing of a specimen at intervals of a few millimetres. Samples a small fraction of the peripheral margin.
curettage and cautery
Scraping the soft tumour out with a curette, then cautery; usually repeated. Depends on tumour being softer than dermis.
deep margin
The base of the excision. Usually clear if a thin layer of subcutaneous fat is taken (CCA).
en face
Sectioning parallel to the margin surface so that the whole peripheral and deep margin is examined, rather than sampled by vertical slices.
hedgehog inhibitor
Oral drug blocking the hedgehog pathway, which is active in almost all BCC: vismodegib, sonidegib. Both have Medsafe approval; neither is funded in New Zealand.
laBCC
Locally advanced BCC. No agreed definition; EADO calls it “a vague term” and uses easy- versus difficult-to-treat instead.
mask area
NZSCD high-risk facial site list: ears, temples, eyes, nose and lips. Narrower than NCCN’s “head and neck, any size”.
micronodular
BCC made of small nests. High risk on every list; clinically indistinguishable from nodular BCC.
morphoeic
Sclerosing or fibrosing BCC: thin tumour strands in a dense fibrous stroma. Ill-defined, extends widely, and cannot be curetted. CCA prefers “fibrosing” to “desmoplastic”.
subclinical extension
Tumour beyond the clinically visible border, invisible to the eye and dermoscope. In BCC it often takes the form of narrow finger-like outgrowths.

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Unresolved as of 1 October 2026. The wording of the NCCN v1.2027 risk table, which may differ from the v2.2026 table quoted here. Public Mohs access outside Auckland, and referral routes to the Auckland service from other regions. Whether methyl aminolevulinate cream is currently supplied in New Zealand. Whether a compassionate-access programme for cemiplimab operates in New Zealand.