Question
Basal cell carcinoma
Answer
Basal cell carcinoma (BCC) is the most common malignant skin tumour, arising from basal keratinocytes of the epidermis, strongly linked to chronic sun (UV) exposure and fair skin, most often affecting sun-exposed areas of the face.
Gross: Classically a pearly, waxy papule/nodule with a raised, rolled border showing prominent telangiectatic vessels; may develop a central ulcer as it grows (“rodent ulcer”). Other variants: superficial (scaly erythematous patch) and pigmented (mimicking melanoma).
Microscopy:
- Nests, cords, and islands of basaloid tumour cells budding off from the epidermis, extending into the dermis.
- Tumour cells are small, with hyperchromatic nuclei and scant cytoplasm, closely resembling normal epidermal basal cells.
- Characteristic peripheral palisading of nuclei at the periphery of the tumour nests (columnar arrangement of the outermost layer of cells).
- Retraction artefact/clefting — separation of tumour nests from the surrounding stroma, a characteristic processing artefact.
- Surrounding stroma often shows mucinous change and a variable inflammatory infiltrate.
Behaviour: Slow-growing but locally invasive and destructive if untreated, capable of invading underlying cartilage/bone (“rodent ulcer”); metastasis is extremely rare.
Treatment: Complete surgical excision (including Mohs micrographic surgery for cosmetically sensitive sites) is generally curative.