Light micrograph of a section through a basal cell carcinoma, a common cancer of the skin. Basal cell carcinoma derives from the basal cells of the epidermis, behaving in a malignant manner by invading the dermis & other underlying structures but almost never metastasizing (spreading to other organs). The cancer appears as a raised area on light-exposed areas of skin, particularly the face. It may ulcerate, giving rise to the colloquial name of rodent ulcer. Histologically, the tumour may be of variable appearance. Here, densely-stained nodular regions of tumour cells are interpsersed with cystic patterns (white unstained areas). Very similar to UFig. 20.5a BASIC HISTOPATHOLOGY