A malignant tumor composed of cells showing differentiation toward sebaceous epithelium. The tumor is solitary, firm, somewhat raised, more or less translucent, and covered with normal or slightly verrucose epidermis. It may be yellow or orange. The face and scalp are the commonest sites. The growth can be slow or rapid but metastasis is uncommon. Surgery cures most of the cases. (From Rook et al., Textbook of Dermatology, 4th ed, pp2403-4).