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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
Key points
- Commonest skin cancer — locally invasive but almost never metastasises
- Nodular BCC (commonest): pearly papule with rolled telangiectatic border and central ulceration
- Superficial BCC: flat, scaly, pink patch on trunk. Morphoeic: waxy, scar-like — most aggressive
- Surgical excision (4 mm margin) is gold standard. Mohs for high-risk sites (face)
- Two-week wait referral for any suspicious skin lesion
Overview
Basal cell carcinoma is the most common malignancy in humans, arising from the basal layer of the epidermis. Locally invasive but metastasis is exceedingly rare (<0.1%). Main risk factor is cumulative UV exposure. Subtypes: nodular (~60%), superficial (~30%), morphoeic/infiltrative (~5-10%). Morphoeic BCCs have highest recurrence risk due to ill-defined margins.
Epidemiology
Over 100,000 cases/year in the UK. More common in fair-skinned individuals (Fitzpatrick I-II). Peak incidence over 60. Risk factors: cumulative UV, immunosuppression (transplant recipients 10x risk), Gorlin syndrome (PTCH1 mutation, multiple BCCs in young patients).
Clinical Features
Symptoms
Slowly growing, painless skin lesion on face
May bleed, crust, or fail to heal
Patient describes "spot that won't go away"
Signs
Nodular: pearly, flesh-coloured papule with rolled telangiectatic border
Central ulceration or crusting (rodent ulcer)
Superficial: flat, scaly, erythematous patch with fine pearly border — often on trunk
Morphoeic: waxy, scar-like plaque with ill-defined borders
Pigmented BCC (contains melanin) — can mimic melanoma
Investigations
First-line
DermoscopyArborising vessels, leaf-like areas, blue-grey ovoid nests
Excision biopsyPreferred — diagnostic and therapeutic
Second-line
Punch biopsyIf excision not immediately practical — to confirm diagnosis/subtype
Management
BAD Guidelines on BCC + NICE CKS1
Referral
- Two-week wait referral for any suspicious skin lesion
2
Surgical excision (gold standard)
- Standard excision with 4 mm peripheral margin
- Mohs micrographic surgery for high-risk: nose, periorbital, ears, morphoeic, recurrent
- Mohs achieves ~99% cure rate
3
Non-surgical (selected low-risk superficial BCCs)
- Topical imiquimod 5% cream 5 nights/week for 6 weeks
- Topical 5-fluorouracil
- Photodynamic therapy
- Curettage and cautery for small superficial/nodular BCCs
4
Follow-up
- Sun protection education and self-examination
- Annual skin check for 3-5 years — risk of second BCC is 30-50%
Complications
- Local invasion: Can erode into cartilage, bone, orbit if neglected
- Incomplete excision: Requires re-excision or Mohs
- Recurrence: ~5% after standard excision, <1% after Mohs
UKMLA Exam Tips
- 1Pearly papule + rolled telangiectatic border + central ulceration on sun-exposed face = nodular BCC
- 2BCCs almost NEVER metastasise — distinguish from SCC and melanoma
- 3Morphoeic BCC: scar-like, ill-defined, most aggressive — needs Mohs
- 4Gorlin syndrome: multiple BCCs in young patients + jaw cysts + calcified falx cerebri
- 5Arborising vessels on dermoscopy = BCC discriminator
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