DermatologyTier 1Disease (DEADMAN)

Cutaneous oncology - basal cell carcinoma

Description

Commonest skin cancer and commonest cancer overall - locally invasive, essentially never metastasises
Subtypes: nodular (commonest, pearly papule with telangiectasia), superficial (scaly patch, trunk), morphoeic/infiltrative (scar-like, ill-defined, higher recurrence risk), pigmented

Australia has among the highest incidence rates worldwide
Risk rises with cumulative UV exposure, age, fair skin (Fitzpatrick I-II), immunosuppression

UV-induced DNA damage to basal keratinocytes, with PTCH1/hedgehog pathway mutations driving unregulated growth
Additional risk: prior radiotherapy, arsenic exposure, chronic immunosuppression (transplant recipients), basal cell naevus syndrome (Gorlin syndrome - multiple BCCs at young age)

Clinical + dermoscopy (arborising telangiectasia, blue-grey ovoid nests, ulceration)
Biopsy for histological confirmation and subtype - guides margin/treatment choice (high-risk subtypes - morphoeic, infiltrative, micronodular - need wider margins/Mohs)
High-risk site (H-zone of face), size >2cm, recurrent lesion, or aggressive histology - refer for specialist management

Surgical excision with margins (4mm standard low-risk; wider or Mohs micrographic surgery for high-risk site/histology/recurrent lesions) - gold standard, lowest recurrence
Mohs micrographic surgery - highest cure rate, tissue-sparing, preferred for high-risk facial sites
Superficial BCC, low-risk sites: topical imiquimod or 5-fluorouracil, or cryotherapy/curettage and electrodessication - lower cure rates than surgery, appropriate for select cases
Radiotherapy - non-surgical candidates or adjuvant for incompletely excised high-risk lesions
Advanced/metastatic (rare): hedgehog pathway inhibitors (vismodegib, sonidegib)
Lifelong sun protection and skin surveillance - high risk of a subsequent new BCC

Multiple BCCs common (field-cancerised skin from cumulative UV damage)
Actinic keratosis, SCC, melanoma - all share the UV-damage field, surveillance covers all three
Gorlin syndrome - multiple BCCs, jaw cysts, skeletal anomalies

Slow-growing, locally invasive, essentially never metastasises - mortality is very low but local tissue destruction can be extensive if neglected (esp. periorbital/nasal)
High recurrence risk with morphoeic/infiltrative subtypes and incomplete excision
Patients with one BCC have a substantially increased risk of further skin cancers - require ongoing surveillance

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