Primary choroidal melanoma in a patient with previous cutaneous melanoma.

A 67-year-old woman with a history of a skin melanoma that was excised 7 years previously had a 6-month history of decreased vision in her right eye. A choroidal melanoma was diagnosed clinically, and the eye was enucleated. The results of a histopathological examination revealed a primary uveal melanoma. Slides of the skin melanoma were obtained, and the initial diagnosis was confirmed. In an attempt to illustrate a biological difference between the 2 melanomas, immunohistochemical studies were performed on sections of the 2 specimens using S-100 protein, HMB-45, and S-100-beta. Primary cutaneous and choroidal melanomas appearing in a patient with no predisposition are rare; this is believed to be only the fifth such case reported in the literature.

Immunohistochemical expression of S-100 beta in choroidal melanomas.

OBJECTIVE: To investigate the expressivity of S-100 beta antibodies in choroidal melanomas and to compare it with that of S-100 protein and HMB-45. DESIGN: Twenty-seven choroidal melanoma specimens obtained from the McGill University Ophthalmic Pathology Registry were classified as spindle cell, epithelioid cell or mixed-cell type. Immunohistochemistry was performed using the standard peroxidase-antiperoxidase technique with monoclonal HMB-45, polyclonal S-100, polyclonal S-100 beta and monoclonal S-100 alpha beta antibodies in formalin-fixed, paraffin-embedded sections. OUTCOME MEASURE: Intensity of immunoreaction. The result was considered positive when at least five focal areas of stained cells were observed within the tumour. RESULTS: All 27 tumours were positive for HMB-45, 19 (70%) for S-100, 23 (85%) for S-100 beta, and 21 (78%) for S-100 alpha beta. No correlation was found between the intensity of the immunoreaction and cell classification. CONCLUSIONS: HMB-45 is the most reliable marker for choroidal melanomas. S-100 beta is a more sensitive marker than S-100 for choroidal melanomas regardless of cell type. Contrary to previous reports, S-100 beta should not be considered a useful immunomarker to differentiate between primary choroidal melanoma and cutaneous melanoma metastatic to the choroid.