Conjunctival Melanoma: Current Management.

Abstract

Conjunctival melanoma is a rare, potentially lethal cancer that mainly affects fair-skinned individuals. The tumor mostly arises from primary acquired melanosis (PAM) with atypia. The presentation of conjunctival melanoma varies and should be clinically differentiated from an array of ocular surface pigmented and nonpigmented lesions. Mutations in the oncogenes BRAF (V600E) and NRAS, and the tumor suppressor gene NF1, are associated with worse survival. UV signature mutations are frequently observed in the bulbar conjunctival melanoma. The TNM staging classifies conjunctival melanoma according to its location and extent. The treatment of conjunctival melanoma depends on tumor staging. Surgical excision of a localized bulbar or forniceal tumor with the no-tumor-touch technique and margin cryotherapy can be sufficient for local control. Adjunctive radiotherapy options include Proton beam radiotherapy, Plaque radiotherapy for ocular surface melanoma, Orthovoltage (Deep x-ray) radiotherapy for palpebral melanoma, and Megavoltage LINAC-based photon radiotherapy can be used for locally invasive and localized orbital extension of conjunctival melanoma. Topical mitomycin-C eye drops are used for diffuse flat melanoma or PAM with severe atypia. Systemic targeted therapy such as BRAF inhibitors for melanoma with BRAF mutation, and systemic immunotherapy drugs have been recently used for more extensive or metastatic disease. Risk factors for metastasis include: greater tumor thickness, non-bulbar location, low tumor pigmentation, histologic ulceration, >1 mitotic figure per mm2, and adjacent structures invasion. Localized tumors should be excised en block, and incisional biopsy should be avoided, which could lead to local widespread tumor dissemination and subsequent recurrence and metastasis.