PATHOLOGY OF OCULAR MELANOMAS

Primary ocular melanomas usually arise in the uvea, in the choroid and ciliary body. They metastasize primarily and initially exclusively, to the liver. Metastasis and survival is determined by the maximum tumour dimension, the number of epithelioid cells present within the tumour, vascular patterns within the tumour and nucleolar size and activity. Ganglioside and integrin profiles differ from cutaneous melanomas. Iris melanocytic lesions tend not to metastasize, most being naevi of varying degrees of aggressiveness which may cause glaucoma and corneal decompensation. Conjunctival melanoma is a rare unilateral tumour arising either in primary acquired melanosis or de novo rather than within a naevus. Survival of the patient depends on the location of the tumour and the histological subtype. Tumours not arising in the bulbar or limbal conjunctiva have a much poorer prognosis as do eyelid (cutaneous) melanomas if they involve the lid margin.