Purpose: True neoplasm (adenocarcinoma) of retinal pigment epithelium (RPE) is very rare; since it can be misdiagnosed as intraocular malignant melanoma it is of importance to know the clinical and pathologic aspects of this neoplasm. Here, we report a case of adenocarcinoma of RPE.

Methods: Case report.

Results: A 60-year-old man with progressive loss of the vision of the right eye was enucleated with a clinical diagnosis of malignant melanoma. Grossly, a solid well-circumscribed mass occupying the posterior section of the globe near the optic disc was observed. In histological evaluation, the tumor was composed of cells having large, pleomorphic, and hyperchromatic nuclei and prominent nucleoli with occasional pigmentation. Tumor cells were mostly arranged in a papillary pattern. To differentiate it from melanoma, immunohistochemistry was performed. Epithelial membrane antigen (EMA) was strongly positive and HMB45 was negative; this is consistent with the diagnosis of adenocarcinoma of RPE. On systemic evaluation no metastases was found.

Conclusion: Adenocarcinoma of RPE is very rare but it should be considered in the differential diagnosis of malignant melanoma of the eye.