Clear cell differentiation in choroidal melanoma. COMS report no. 8. Collaborative Ocular Melanoma Study Group.
OBJECTIVE
To describe 2 enucleated eyes of patients enrolled in the Collaborative Ocular Melanoma Study that contained primary choroidal melanoma with clear cell features.


METHODS
During a 9-year period, 1493 eyes enucleated as part of the Collaborative Ocular Melanoma Study routinely processed for histologic examination were evaluated by the pathology review committee (H.E.G, D.M.A, and W.R.G). Two eyes with unusual variants of choroidal melanoma were identified and immunostained for S100 protein and HMB 45. Portions of the tumors were processed for electron microscopic examination.


RESULTS
Results of electron microscopic examination of both tumors displayed malignant melanoma (mixed cell type with many malignant cells with clear cytoplasm). The cytoplasm of the clear cells stained with periodic acid-Schiff and failed to stain when pretreated with diastase. Results of immunohistochemical stains in both tumors were positive for S100 protein and HMB 45 in the tumor cells. Results of electron microscopic examination showed that the cytoplasm of the clear cells contained scattered glycogen granules, premelanosomes, and melanosomes.


CONCLUSIONS
These cases represent a clear cell variant of malignant melanoma of the choroid. This tumor should not be confused with metastatic clear cell carcinoma to the choroid.
Grossniklaus
H E
HE
Department of Ophthalmology, Emory University School of Medicine, Atlanta, Ga, USA.
Albert
D M
DM
Green
W R
WR
Conway
B P
BP
Hovland
K R
KR
D000368:Aged; D000951:Antigens, Neoplasm / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D002455:Cell Division; D002830:Choroid Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D003937:Diagnosis, Differential; D015353:Eye Enucleation; D017809:Fatal Outcome; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008545:Melanoma / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D058950:Melanoma-Specific Antigens; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis; D009364:Neoplasm Recurrence, Local; D009418:S100 Proteins / Q000032:analysis
D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins; D009418:S100 Proteins