Differentiation of pigmented conjunctival squamous cell carcinoma from melanoma.

A 69-year-old man developed a pigmented conjunctival tumor that had a papillomatous vascular configuration but no leukoplakia. Although the pigmentation suggested melanoma clinically, histopathologic study of the resected lesion disclosed squamous cell carcinoma, with scattered dendritic melanocytes in the tumor. Conjunctival squamous cell carcinoma can be pigmented, similar to melanoma. The papillomatous arrangement of blood vessels in such tumors should strongly suggest squamous cell carcinoma despite the absence of leukoplakia.