Nevus of Ota (oculodermal melanocytosis) in a dog

Current Therapeutics and Future Perspectives to Ocular Melanocytic Neoplasms in Dogs and Cats

Neoplasms of melanocytic origin are diseases relevant to dogs and cats' ophthalmic oncology due to their incidence, potential visual loss, and consequent decrease in life quality and expectancy. Despite its non-specific clinical presentation, melanocytic neoplasms can be histologically distinguished in melanocytomas, which present benign characteristics, and malignant melanomas. The diagnosis often occurs in advanced cases, limiting the therapeutic options. Surgery, cryotherapy, radiotherapy, photodynamic therapy (PDT), and laser are currently available therapeutic strategies. As no clinical guidelines are available, the treatment choice is primarily based on the clinician's preference, proficiency, and the owner's financial constraints. While surgery is curative in benign lesions, ocular melanomas present a variable response to treatments, besides the potential of tumour recurrences or metastatic disease. This review presents the currently available therapies for ocular melanocytic neoplasms in dogs and cats, describing the therapeutic, indications, and limitations. Additionally, new therapeutics being developed are presented and discussed, as they can improve the current treatment options.

Concurrent lacrimal gland melanocytoma and ocular melanocytosis in a dog

A 9-y-5-mo-old, spayed female, mixed-breed dog with buphthalmia and elevated intraocular pressure in the left eye, consistent with glaucoma, was evaluated. Black-pigmented, slightly elevated tissue with irregular margins was noted on the dorsolateral aspect of the left globe. Ultrasonography detected a mass, later identified as lacrimal gland, adjacent to the globe and the thickened uvea. The surgically removed lacrimal gland was effaced by dense sheets of melanin-laden cells. Within the enucleated globe, numerous melanin-laden cells infiltrated and expanded the rostral two-thirds thickness of the cornea, the entire anterior uvea (iris and ciliary body), and a rostral portion of the choroid. Melanin-laden cells in the left lacrimal gland and globe showed no nuclear atypia or mitotic figures, and reacted to anti-S100 and anti-melan A antibodies by immunohistochemistry. Our final diagnosis was concurrent lacrimal gland melanocytoma and ocular melanocytosis. The trabecular meshwork of the eye was obliterated by melanin-laden cells, which was the likely cause of glaucoma in this patient. To our knowledge, melanocytoma affecting the lacrimal gland has not been reported previously in a non-human mammalian species. Veterinary clinicians are encouraged to include melanocytoma in the differential list when examining an enlarged lacrimal gland.

Oculodermal Melanocytosis: Nevus of Ota in a Dog

This report describes the clinical presentation, diagnosis, and histopathologic features of oculodermal melanocytosis in a young dog. A 3-year-old male neutered Labrador Retriever presented with conjunctival and scleral hyperpigmentation of the right eye, with concurrent ipsilateral cutaneous hyperpigmentation involving the right side of the face. Initial skin and conjunctival biopsies revealed an accumulation of histologically benign melanocytes within the dermis and conjunctival stroma, respectively. Enucleation was elected 19 months later by the referring veterinarian due to the progression of ocular pigmentation with concurrent marked corneal lipidosis and the suspicion of a scleral mass. On gross and histopathologic examination of the globe, there was marked panuveal melanocytosis with extension into the sclera, bulbar conjunctiva, and connective tissue surrounding the optic nerve, as well as sharply demarcated ipsilateral hyperpigmentation of the facial skin. The findings are characteristic of oculodermal melanocytosis (nevus of Ota), a dermal melanocytic hamartoma presenting as cutaneous facial hyperpigmentation that corresponds to the distribution of the ophthalmic and maxillary branches of the trigeminal nerve, often with ipsilateral ocular involvement.