Paper II
Question
Basal cell carcinoma of the skin
Answer
Basal cell carcinoma (BCC) is the most common malignant skin tumour, arising from the basal layer of the epidermis and its appendages.
- Risk factors: Chronic sun (UV) exposure, fair skin, and older age; occurs most often on sun-exposed areas of the face (e.g., upper lip, forehead, around the eyes).
- Gross: Classically presents as a slow-growing, pearly/waxy papule or nodule with a rolled, telangiectatic border, which may later ulcerate centrally (“rodent ulcer”).
- Microscopy: Nests and cords of basaloid cells (resembling epidermal basal cells) with hyperchromatic nuclei and scant cytoplasm, showing characteristic peripheral palisading of the nuclei at the edges of the tumour nests, with retraction artefact (clefting) separating the tumour nests from the surrounding stroma.
- Behaviour: Locally invasive and destructive (“rodent ulcer” — can invade cartilage/bone if neglected) but has an extremely low metastatic potential.
- Treatment: Surgical excision (including Mohs micrographic surgery) is usually curative.