| Origin |
Basal cells of epidermis |
Keratinocytes of epidermis |
Melanocytes |
| Incidence |
Most common skin cancer |
Second most common |
Less common but most deadly |
| Malignant Potential |
Rarely metastasizes |
Low–moderate metastatic risk |
High metastatic potential |
| Growth |
Slow-growing, locally invasive |
Faster-growing, may invade locally |
Variable; often rapid vertical growth (nodular type) |
| Common Sites |
Sun-exposed: nose, eyelids, cheeks |
Sun-exposed: face, ears, scalp, lips |
Men: back; Women: legs; face/arms also |
| Appearance |
Pearly, translucent nodule; telangiectasia; central ulcer “rodent ulcer” |
Scaly, keratotic, firm nodule; may ulcerate; cutaneous horn |
Pigmented lesion; ABCDE: asymmetry, border irregularity, colour variegation, diameter >6mm, evolution |
| Variants |
Nodular, superficial, morpheaform |
Keratoacanthoma, invasive SCC |
Superficial spreading, nodular, lentigo maligna, acral lentiginous |
| Metastasis Risk |
Very low |
Low (high-risk sites: lip, ear, immunosuppressed) |
High; common to lymph nodes, lung, liver, brain |
| Investigations |
Usually clinical; biopsy if uncertain |
Clinical + biopsy; imaging if high-risk |
Excisional biopsy; Breslow thickness, sentinel node, imaging if metastasis suspected |
| Management |
Surgical excision (Mohs for high-risk); topical for superficial lesions |
Surgical excision (Mohs for high-risk); radiotherapy if inoperable |
Wide local excision; sentinel node biopsy; systemic therapy (immunotherapy, targeted therapy) |
| Prognosis |
Excellent if treated |
Good if treated; depends on depth/site |
Variable; poor if advanced/metastatic |
