Pigmented squamous cell carcinoma of the conjunctiva. A clinicopathologic ultrastructural study.

The clinical and morphologic features of a pigmented squamous cell carcinoma of the bulbar conjunctiva in a 57-year-old black man are reported. The tumor resembled the more usual epibulbar squamous cell carcinoma but had many melanin containing cells within it. Transmission electron microscopy disclosed melanosomes within squamous epithelium, melanocytes, and macrophages. The only cells within the tumor with morphologic features of a malignant neoplasm were squamous in type. The literature on this rare conjunctival tumor, which has a good prognosis following complete excision, is reviewed. Pigmented squamous cell carcinomas need to be distinguished from the more common nodular melanomas, which have a more ominous outlook.