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Dermatology

Basal Cell Carcinoma

Basal cell carcinoma (BCC) is the most common human malignancy, arising from basal keratinocytes after cumulative UV damage. Slow-growing, locally destructive, and rarely metastatic.

Last reviewed 24 May 2026 - MedicoMedics editorial team

Basal cell carcinoma pearly nodule with telangiectasia

Pathophysiology

Chronic UV-B exposure induces PTCH1 mutations, activating the Hedgehog/GLI pathway in basal keratinocytes. Fair skin (Fitzpatrick I-II), immunosuppression, arsenic exposure and Gorlin syndrome markedly raise risk.

Sources: NCCN Basal Cell Skin Cancer (v2.2025); AAD Guidelines of Care for BCC (J Am Acad Dermatol 2018;78:540); BAD BCC Guidelines (Br J Dermatol 2021;185:899)

Clinical presentation

Pearly, translucent papule with rolled borders, central telangiectasia and possible ulceration ('rodent ulcer') on sun-exposed skin (face, ears, scalp). Morpheaform and infiltrative subtypes are scar-like and aggressive.

Diagnosis

Dermoscopy reveals arborising vessels and blue-grey ovoid nests. Confirm with shave or punch biopsy; report subtype (nodular, superficial, infiltrative, morpheaform) which drives treatment.

Management

Low-risk (superficial/nodular, trunk, <2 cm): electrodesiccation and curettage, cryotherapy, topical imiquimod or 5-FU. High-risk or facial 'H-zone': Mohs micrographic surgery. Locally advanced or metastatic: hedgehog inhibitors (vismodegib, sonidegib); cemiplimab for hedgehog-refractory disease.

Prevention & follow-up

Daily broad-spectrum SPF 30+, sun-protective clothing, and full-skin exam every 6-12 months - patients have ~50% risk of a second BCC within 5 years.

Sample USMLE-style MCQs

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Question 1

A 72-year-old fair-skinned farmer has a 6-mm pearly papule on his nose with rolled borders and central ulceration. Biopsy shows palisading basaloid nests. What is the best treatment?

Question 2

Which molecular pathway is constitutively activated in most sporadic BCC?

Question 3

A patient with metastatic BCC progresses on vismodegib. Which agent is FDA-approved next?

Question 4

A 25-year-old with multiple BCCs, jaw cysts and palmar pits most likely has:

Question 5

Which BCC subtype has the highest recurrence and requires wider margins?

References

Primary guidelines and peer-reviewed sources used for this entry. Reviewed 24 May 2026 by MedicoMedics editorial team.

  1. NCCN Basal Cell Skin Cancer (v2.2025)
  2. AAD Guidelines of Care for BCC (J Am Acad Dermatol 2018;78:540)
  3. BAD BCC Guidelines (Br J Dermatol 2021;185:899)

Frequently asked

Why is Mohs preferred on the face?

Tissue-sparing with 99% 5-year cure; critical for cosmetic units and recurrent tumours.

Does BCC metastasise?

Extremely rare (<0.1%); locally destructive is the primary concern.

What is Gorlin syndrome?

Autosomal dominant PTCH1 mutation: multiple BCCs before 30 y, jaw keratocysts, palmar pits, medulloblastoma.

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