Retinal pigment epithelium adenoma in vitreous fluid cytology

Ocular cytology specimens are relatively uncommon, adding to the difficulty of their evaluation by cytopathologists. While melanomas account for a majority of primary intraocular pigmented lesions, other diagnostic considerations must be included in the differential. This brief report highlights a case of a pigmented ocular lesion in a 24-year-old man and key morphologic, immunohistochemical, and clinical differences between melanoma, melanocytoma, choroidal nevus, and retinal pigment epithelium (RPE) adenoma.