Learning Objective
Describe the epidemiology, risk factors, clinical features, histopathology, variants, molecular basis, and management of basal cell carcinoma.
Overview
- BCC is the most common tumor in adults in Western countries.
- Arises from the basal cells of hair follicles.
- Most common in middle-aged and elderly individuals.
Risk Factors
| Risk Factor |
Explanation / Mechanism |
| Chronic sun exposure |
UV-induced DNA damage |
| Fair complexion |
Low melanin protection |
| Immunosuppression |
Reduced immune surveillance |
| Xeroderma pigmentosum |
DNA repair defect |
| Genetic predisposition |
Hedgehog pathway mutations |
Clinical Features
- Location: Sun-exposed, hair-bearing areas, especially the face
- Lesion appearance:
- Pearly papules
- Nodules with heaped-up, translucent borders
- Telangiectasias
- Ulceration (“rodent ulcer”)
- Growth: Slow, locally invasive, rarely metastasizes
Histopathology
- Invasive nests of basaloid cells
- Peripheral palisading of nuclei
- Stromal retraction (clefting) between tumor nests and surrounding tissue
- Variable pigmentation in some cases
Molecular Basis
- Mutations in the Hedgehog signaling pathway (e.g., PTCH1, SMO)
- Seen in sporadic and familial cases (e.g., Gorlin syndrome)
Activity
Management and Prognosis
| Treatment |
Notes |
| Complete surgical excision |
Curative; preferred method |
| Mohs micrographic surgery |
High-risk or cosmetically sensitive areas |
| Shave biopsy |
50% recurrence rate |
| Prognosis |
Excellent; metastasis is extremely rare |
High-Yield Points
- BCC is slow-growing but locally aggressive
- Most arise in sun-exposed areas in older adults
- Histology: basaloid nests with palisading
- Hedgehog pathway is key in pathogenesis
- Complete excision is curative; shave biopsies have high recurrence
Activity
