To characterize the immunophenotypic expression pattern of conjunctival melanomas, with the use of standard melanoma markers as well as microphthalmia transcription factor and p75 neurotrophin receptor.
Eleven conjunctival melanomas, including 1 caruncular melanoma, were immunolabeled with a panel of antibodies that included S100, tyrosinase, melan-A, HMB-45 and HMB-50 combination, microphthalmia transcription factor, and p75 neurotrophin receptor. The results were tabulated on the basis of intensity and pervasiveness of labeling and compared with a previous study of uveal melanomas.
Immunolabeling with S100 was at significantly higher levels in conjunctival melanomas than in uveal melanomas. Tyrosinase, HMB-45 and HMB-50 combination, melan-A, and microphthalmia transcription factor were expressed at high levels in conjunctival melanomas, whereas p75 neurotrophin receptor was not expressed.
Melanomas of the conjunctiva, including the caruncle, expressed S100, tyrosinase, melan-A, HMB-45 and HMB-50 combination, and microphthalmia transcription factor at high levels, suggesting that these are good markers for this melanoma subtype. Expression of S100 was significantly higher in conjunctival melanomas than in uveal melanomas. The immunophenotypic pattern of conjunctival melanomas is most similar to the epithelioid subtype of cutaneous melanomas.