An unusual case of ocular melanosis and limbal melanocytoma with benign intraorbital extension in a dog.

Publications // Richard Dubielzig // Jul 01 2013

PubMed ID: 23134502

Author(s): Dees DD, Maclaren NE, Teixeira L, Dubielzig RR. An unusual case of ocular melanosis and limbal melanocytoma with benign intraorbital extension in a dog. Vet Ophthalmol. 2013 Jul;16 Suppl 1:117-22. doi: 10.1111/vop.12009. Epub 2012 Nov 7. PMID 23134502

Journal: Veterinary Ophthalmology, Volume 16 Suppl 1, Jul 2013

This case report describes concurrent ocular melanosis and limbal melanocytoma in a 6-year-old Golden Retriever dog. Three years prior, the pet was examined for progressive corneal pigmentation and started on topical Tacrolimus but was subsequently lost to followup. Current ophthalmic examination revealed a large pigmented limbal mass and severe corneal pigmentation of the left eye as well as a small focal raised pigmented mass of the right third eyelid. Due to extent and rapidity of tumor growth, the left eye was removed via transconjunctival enucleation and submitted for histopathologic examination. At the time of surgery, numerous orbital structures including intraorbital fat, extraocular muscles, and portions of the proximal nasolacrimal drainage apparatus contained multifocal areas of black pigmentation. These tissues were subsequently removed and submitted for microscopic analysis. The pigmented mass of the right third eyelid was also excised. Histopathology of the left eye and orbital contents revealed a limbal melanocytoma extending to the bulbar conjunctiva and orbital space forming a large, markedly necrotic mass. Diffuse, severe ocular melanosis, abnormal stromal pigmentation of the sclera and orbital tissues, and corneal stromal pigmentation were noted. The mass of the right third eyelid was confirmed to be a conjunctival melanocytoma. To the authors’ knowledge, this is the first report of concurrent ocular melanosis and limbal melanocytoma with orbital infiltration. The peculiar multifocal distribution of melanocytes throughout ocular connective tissues may explain the development of multiple melanocytic lesions in this patient.

© 2012 American College of Veterinary Ophthalmologists.