Sebaceous Carcinoma

Higher magnification of a sebaceous carcinoma showing a haphazard mixture of basaloid germinative cells (predominant cell population) and smaller numbers of more mature-appearing sebaceous cells with clear or lightly eosinophilic cytoplasm. The basaloid cells have round or oval vesicular nuclei, prominent nucleoli and brisk mitotic activity. Comedonecrosis is often present. There may be perineural and lymphatic/vascular invasion. Poorly-differentiated cases are composed almost entirely of pleomorphic basaloid cells and have only rare foci of lipid-containing differentiated sebaceous cells. Some cases show prominent keratinization which may lead to diagnostic confusion with squamous cell carcinoma.