Carcinomas of sebaceous glands are uncommon. They are traditionally classified into ocular and extraocular sebaceous carcinomas (SC). Ocular SC tend to be more common and more aggressive than extraocular SC. However, the latter can occasionally follow a fatal course. Histologically, SC should be classified into 1) SC in situ; 2) SC, infiltrating, low-grade with or without pagetoid spread; 3) SC, infiltrating, high-grade, with or without pagetoid spread; and 4) SC with extraocular and extracutaneous involvement, including metastases. Immunohistochemistry plays a minor role in the diagnosis of SC. Thomsen-Friedenreich (T) antigen can be a helpful tool in differentiating SC (strong T-antigen reactivity in basaloid cells) from other mimicking neoplasms (basaloid cells are T-antigen negative). The histologic differential diagnosis, pathogenesis, and management of SC are reviewed.