Clear cell squamous cell carcinoma. A histologic, immunohistologic, and ultrastructural study.

Squamous cell carcinomas (SCCs) usually show a standard histopathologic picture only varying with regard to their degree of differentiation. The authors describe a case of clear cell SCC that was studied by light and electron microscopy. The clear cells showed an empty cytoplasm that was periodic acid-Schiff and alcian blue negative. By electron microscopy these cytoplasms consisted of empty spaces and were not surrounded by membranes, which would be consistent with lipid vacuoles. The differential diagnosis of this uncommon variant of SCC requires consideration of other clear cell tumors.