Sebaceous carcinoma is a rare malignant tumor derived from the epithelium of sebaceous glands. It potentially may develop from any sebaceous gland, but most commonly occurs in the periorbital area. We report a case of sebaceous carcinoma in a 14-year-old girl who was first seen with an asymptomatic 2.5 x 2.3-cm firm, multilobulated cutaneous nodule on the anterior thorax, which had been present for 1 year. She was adopted, and no family history is available. A skin biopsy specimen revealed a poorly differentiated infiltrative carcinoma involving the dermis and subcutaneous fat and focally involving the epidermis. Tumor cells had sebaceous and squamous differentiation. A diagnosis of sebaceous carcinoma was made. She was treated by surgical excision with a 2-cm margin. Further work-up showed no evidence of Muir-Torre syndrome.