Question:

A 78-year old lady presented with a painless firm nodule on left forehead that progressively enlarged over few years, reaching one centimeter in diameter. The centre became ulcerated, with a smooth pearly edge.

Answer: D. Basal cell carcinoma

Basal cell carcinoma BCC is a slow growing, locally invasive tumour that increases in incidence with age. It is common over age of 50 years, on light exposed areas such as face and forehead. Genetic, ultraviolet or X-ray irradiation, inorganic arsenic exposure, and immuno-suppression are known risk factors. The tumour is derived from basal keratinocytes that consists of uniform basophilic cells, in well-defined islands that invade the dermis from epidermis as buds, lobules or strands. Excess melanin deposition may occur in the basal cells to produce a pigmented appearance clinically.

There are several clinical variants. The most common nodular-cystic BCC presents as a smooth pearly papule or nodule with surface telangiectasia. The centre may become ulcerated with rolled edge. Superficial BCC usually presents on the trunk as a red scaly plaque with a pearly edge. Morphoeic BCC presents as a self-healing flat lesion with ill-defined edge that may be mistaken as scar tissue.

Surgical excision is the mainstay of treatment. Radiotherapy may be considered in elderly patients depending on size, location and operative morbidity of the tumour. Cryotherapy, photodynamic therapy, or topical imiquimod have been reported to be useful for treating superficial BCC. Overall recurrence rate of BCC is around 5% in five years.