Key Facts

BCC is the most common malignancy in humans globally. It is slow-growing, locally invasive, and has an excellent prognosis with appropriate treatment. The incidence is rising significantly, particularly in older populations with fair skin.

Epidemiology

• ~150,000 new cases/year in UK
• M:F ratio ~1.5:1
• Incidence increases with age; peak >70 years
• Most common on sun-exposed sites: head and neck (80%), particularly nose
• Rare in individuals with Fitzpatrick skin types V–VI
• Increasing incidence: ~3–5% per year

Aetiology

• UV radiation: cumulative exposure is the dominant risk factor
• Fair skin (Fitzpatrick types I–II), red/blonde hair, blue eyes
• Immunosuppression: organ transplant recipients have 10× increased risk
• Gorlin syndrome (basal cell naevus syndrome): PTCH1 gene mutation — multiple BCCs from young age
• Previous BCC: 30–50% risk of further BCC within 5 years
• Ionising radiation: previous radiotherapy to skin
• Arsenic exposure: historical occupational risk

Pathophysiology

• Arises from basal layer keratinocytes or hair follicle stem cells
• Key pathway: Hedgehog signalling pathway — mutations in PTCH1 (tumour suppressor) or SMO (oncogene)
• Loss of PTCH1 function → constitutive activation of Hedgehog pathway → uncontrolled proliferation
• Slow growth, local tissue invasion, rarely metastasises due to stromal dependence

Nodular BCC (60%)

• Pearly/translucent papule or nodule
• Rolled, raised border with telangiectasia
• Central ulceration ('rodent ulcer') — may bleed and crust
• Most common on face, especially nose

Superficial BCC (25%)

• Flat, erythematous, scaly plaque with a thin pearly border
• Often on trunk (back, shoulders)
• May be multifocal
• Can mimic eczema, psoriasis, or Bowen's disease

Morphoeic (Sclerosing) BCC (5–10%)

• Waxy, scar-like, white/yellow plaque
• Ill-defined margins — often larger than clinically apparent
• May be depressed relative to surrounding skin
• Highest recurrence rate after treatment

Pigmented BCC

• Contains melanin — appears brown/black
• Can mimic melanoma clinically
• More common in darker skin types

Red Flags

• Rapid growth (consider SCC or melanoma)
• Perineural invasion: pain, paraesthesia, cranial nerve palsies
• Orbital invasion: visual changes, proptosis
• Large neglected tumours (>2 cm) on high-risk sites (nose, periorbital, ear)

Bedside

• Dermoscopy: arborising (tree-like) vessels, blue-grey ovoid nests, leaf-like areas, ulceration; absence of pigment network
• Clinical photography: baseline documentation

Biopsy

• Punch biopsy (3–4 mm): confirms diagnosis and subtype — essential before non-surgical treatment
• Excision biopsy: small lesions — diagnostic and therapeutic
• Incisional biopsy: large lesions where subtype determination guides management

Imaging

• CT/MRI: only if deep tissue invasion suspected (periorbital, perineural)
• Not routinely required for standard BCC

Special Tests

• Mohs micrographic surgery mapping: for high-risk sites — complete margin assessment
• Genetic testing: if Gorlin syndrome suspected (young patient, multiple BCCs)

Non-Pharmacological

• Sun protection: SPF 30+, protective clothing, avoidance of peak UV hours
• Patient education: self-examination for new lesions; 30–50% risk of second BCC
• Surveillance: follow-up for high-risk subtypes and immunosuppressed patients

Surgical (Mainstay of Treatment)

• Surgical excision: first-line for most BCCs
  • Low-risk: 4 mm peripheral margin
  • High-risk (morphoeic, recurrent, large): wider margins or Mohs
• Mohs micrographic surgery: gold standard for high-risk sites (periorbital, nasal, periauricular) — complete margin assessment with tissue conservation; cure rate >99%
• Curettage and cautery: suitable for small, well-defined, low-risk nodular/superficial BCCs on trunk/limbs; not for morphoeic or high-risk sites

Pharmacological

• Topical imiquimod 5% cream: for superficial BCC — apply 5 nights/week for 6 weeks; stimulates local immune response via TLR7
• Topical 5-fluorouracil (5-FU) 5% cream: for superficial BCC — apply BD for 3–4 weeks
• Photodynamic therapy (PDT): methylaminolaevulinate (MAL) cream + red light — for superficial and thin nodular BCC; good cosmetic outcome
• Vismodegib 150 mg OD (Hedgehog pathway inhibitor): for locally advanced or metastatic BCC not suitable for surgery/radiotherapy — NICE TA489

Radiotherapy

• Alternative for elderly patients or those unfit for surgery
• Useful for difficult anatomical sites
• Not first-line in young patients (risk of secondary malignancy, poor long-term cosmesis)

Referral Criteria

• NICE NG12: 2-week wait referral for suspected skin cancer
• All suspected BCCs should be referred to dermatology or plastic surgery
• Mohs surgery referral: periorbital, periauricular, nasal, morphoeic, recurrent

• Excellent prognosis overall: 5-year cure rate >95% with appropriate treatment
• Mohs surgery: >99% cure rate for primary BCC
• Recurrence rates: excision 2–5%, curettage 5–10%, morphoeic subtype 10–15% higher
• Metastasis: <0.05% — extremely rare
• 30–50% risk of developing a further BCC within 5 years
• Gorlin syndrome: lifelong risk of multiple BCCs
• Mortality attributable to BCC is very rare — almost exclusively from neglected large tumours with local invasion

BCC Subtype Comparison

Gorlin Syndrome (Basal Cell Naevus Syndrome)