Conjunctival malignant melanoma-associated pseudomelanoma of the apposing tarsal conjunctiva.

Purpose: To describe a case of conjunctival malignant melanoma associated with pseudomelanomatous alteration of the apposing tarsal conjunctiva.

Methods: A 93-year-old woman presented with an elevated, pigmented mass on her superior bulbar conjunctiva. The tumor was associated with increased pigmentation of the apposing superior tarsal conjunctiva. An excisional biopsy of the epibulbar melanoma and pigmented tarsal conjunctiva was performed.

Results: Histopathologic evaluation of the epibulbar tumor revealed epithelioid melanocytes diagnostic of malignant melanoma. Histopathologic evaluation of the pigmented tarsal lesion showed large areas of ulceration and foci of granulation tissue composed of neovascular sprouts arising in the background of a loose connective tissue, with a moderate chronic inflammatory infiltrate. The infiltrate was composed of mature lymphocytes, plasma cells, and scattered histiocytes. Densely packed intracytoplasmic, brown pigment granules that stained positive with HMB 45 were found, attesting to adjacent melanocytes' releasing melanin-laden granules. There was no evidence of malignancy in the pigmented tarsal specimen.

Conclusion: Noncontiguous pigmented conjunctival tumor can be found in apposition to an epibulbar melanoma. Although a limited biopsy could be considered, only a complete resection and histopathologic evaluation can determine whether the entire lesion is free of malignant melanoma.