Large Choroidal Melanocytoma Simulating Choroidal Melanoma: A Difficult Differential Diagnosis and an Inevitable Enucleation

Purpose. To describe a case of choroidal melanocytoma mimicking a melanoma. Methods. Retrospective case report. Patient. A 48-year-old Moroccan woman presented with progressive, painless decreased vision in her left eye for 2 months. Results. Her visual acuity was light perception in the left eye and 20/20 in the right one. Fundus examination and fluorescein angiography of the left eye showed a total retinal detachment with a large superior brownish mass. The clinical examination, B-scan ultrasonography, and magnetic resonance imaging all suggested a malignant melanoma. Consequently, the eye was enucleated. The histopathology later revealed a benign melanocytoma of the choroid. Discussion. Melanocytoma is a rare benign pigmented tumor. It is classically described as a tumor of the optic nerve head, but there are some exceptional case reports of uveal tract locations (iris, ciliary body, and choroid). In such cases, it can be difficult to clinically differentiate a melanocytoma from a malignant melanoma.