Choroidal melanocytoma in a cat.

An 11-year-old male, neutered European cat was presented for anisocoria due to pupillary dilation in the right eye. Ophthalmic findings were restricted to this eye and consisted of a raised, darkly pigmented, retrolental mass associated with retinal detachment. Ultrasonography identified the mass lesion protruding into the vitreous cavity from the posterior pole of the eyeball and confirmed the detachment of the retina. A tentative diagnosis of an intraocular tumor was made. Radiographic evaluation and retromandibular lymph node cytology did not reveal evidence of distant metastasis. Orbital exenteration of the affected eye was performed and the tumor was diagnosed as a choroidal melanocytic tumor with no criteria of malignancy (melanocytoma). The cat died 5 months later from renal lymphoma, and necropsy did not detect metastasis of the melanocytic tumor. To our knowledge this is the first reported case of feline choroidal melanocytoma.