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Basal cell carcinoma (BCC)
BCC is the most common cancer in humans; it grows slowly, invades and destroys tissue locally but almost never metastasises, so treatment is driven by the risk of local recurrence rather than the risk of spread.
Why it matters in the exam
Exam stems show a pearly papule with telangiectasia on the nose or cheek of an older fair-skinned adult, or a non-healing ulcer with rolled edges. The question turns on separating BCC from SCC, keratoacanthoma and amelanotic melanoma, and on choosing standard excision versus Mohs surgery. Further questions cover Gorlin syndrome, topical treatment of superficial BCC and Hedgehog pathway inhibitors in advanced disease. Remember the risk factors too: fair skin, childhood sun exposure, repeated sunburns, prior ionising radiation, arsenic exposure and immunosuppression. A patient with one BCC is at high risk of another and needs periodic skin checks and sun-protection advice. Prevention includes broad-spectrum sunscreen, clothing, a hat and avoiding tanning beds.
Key points
- BCC is the most common human cancer, linked to intermittent sun exposure and fair skin, and usually driven by a Hedgehog pathway mutation (PTCH1).
- The classic look is a pearly papule with telangiectasia and rolled edges, sometimes with a central ulcer, mostly on the face.
- Metastasis is very rare, so the main danger is local destruction and recurrence, especially in the morpheaform subtype and the facial H-zone.
- Mohs surgery is reserved for high-risk lesions; superficial BCC is treated with imiquimod, 5-FU, PDT or curettage; standard excision with 4 mm margins suits low-risk lesions.
- Advanced disease unsuitable for surgery or radiotherapy is treated with Hedgehog inhibitors, and cemiplimab after their failure.
Summary table
| Subtype | Clinical look | Recurrence risk | Preferred treatment |
|---|---|---|---|
| Nodular | Pearly translucent papule, telangiectasia, sometimes a central ulcer | Low when small and outside the facial H-zone | Excision with 4 mm margins; Mohs in the H-zone |
| Superficial | Pink scaly patch or plaque on the trunk with a thin thread-like border | Low | Topical imiquimod 5%, 5-FU, photodynamic therapy (PDT) or curettage |
| Morpheaform / infiltrative | Scar-like whitish plaque with ill-defined borders | High because of subclinical extensions | Mohs surgery or excision with complete margin control |
| Pigmented | Brown-bluish nodular lesion that mimics melanoma | Depends on growth pattern | Excision; dermoscopy helps (maple-leaf areas, arborizing vessels) |
| Locally advanced or metastatic | Invasion of bone, eye or nerves; metastases very rare | Very high | Multidisciplinary team; vismodegib or sonidegib; radiotherapy; cemiplimab after failure |
In the full version for subscribers
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Sources
- NCCN Guidelines Basal Cell Skin Cancer, 2025 — Treatment by risk group
- British Association of Dermatologists guideline for basal cell carcinoma, 2021 — Surgical and non-surgical management
- EADV/EDF/EORTC European consensus on basal cell carcinoma, 2023 — Diagnosis and treatment
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.