Contributor: Gordon K. Klintworth
The conjunctival melanoma is uncommon and it occurs about one-tenth as frequent as uveal melanomas [melanoma - uvea]. It may be pigmented or amelanotic and it may be preceded by primary acquired conjunctival melanosis, a nevocellular nevus [nevus - nevocellular] or develop in an area of apparently normal conjunctiva. An ephelis does not evolve into a melanoma. Conjunctival melanomas are often apparently multicentric, especially when preceded by primary acquired conjunctival melanosis and histological evidence of this disorder  is found in ~67% of conjunctival melanomas. The biological behavior of conjunctival melanomas is unpredictable, but ~25% of affected individuals die from metastases within 8 years. Spread by lymphatic vessels to the preauricular and intraparotid lymph nodes is common. The nature of the initial lesion does not seem to have prognostic significance. A conjunctival melanoma needs to be differentiated from benign conjunctival lesions (ephelis, primary acquired conjunctival melanosis, congenital ocular melanosis, oculodermal melanocytosis, nevocellular nevus, benign aquired conjunctival melanosis [melanosis - benign acquired]). A primary conjunctival melanoma also needs to be distinguished from an extraocular extension of a melanoma arising in the ciliary body [melanoma - ciliary body] or anterior choroid [melanoma - choroid].