Choroidal melanocytic tumors in dogs: A retrospective study

Abstract

Objective To describe clinical features of dogs diagnosed with choroidal melanocytic tumors at a veterinary teaching hospital. Animals studied Retrospective case series of 13 dogs (14 melanocytic tumors) with choroidal melanocytic tumors. Procedures Medical records of dogs evaluated by the Cornell University ophthalmology service with a clinical diagnosis of a choroidal melanocytic tumor between 2008 and 2020 were reviewed. A choroidal melanocytic tumor was clinically defined as any well‐demarcated, raised pigmented choroidal lesion underlying the retina. Histopathology results were consulted when available. Signalment and clinical features were recorded, including fundoscopic location, histopathologic findings, treatment, and outcome. Results Choroidal melanocytic tumors were identified in 14 eyes of 13 dogs. The mean (±standard deviation) of dogs was 8.6 (±3.5) years. Seven different breeds were represented, with Labrador/Labrador mix being the most common. Ten of the 14 melanocytic tumors were diagnosed incidentally. Four dogs presented for vision loss and ocular discomfort, and diagnosis was made on histopathology examination following enucleation. Pulmonary metastasis was suspected in one dog with an incidentally found choroidal melanocytic tumor OD. Fundoscopic location was available for 8 melanocytic tumors, with 6 (75%) located in the tapetal fundus. Histopathologic diagnosis was melanocytoma for 3 and malignant melanoma in 1 globe, with optic nerve head invasion in 50%. Local recurrence was not seen in any orbit following enucleation. Conclusion Choroidal melanocytic tumors are uncommon in dogs. Metastasis appears to be rare and was only suspected in one dog, but intraocular tumor growth can lead to retinal detachment, glaucoma, and necessitate enucleation.

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

“…In dogs, the melanocytic neoplasms reported in the conjunctiva [ 10 , 39 ] and the orbit [ 2 , 20 ] are predominantly malignant, while those originating in the eyelid (see Figure 1 D), the limbus and the uvea are predominantly benign [ 1 , 2 , 5 , 6 , 20 , 29 , 40 ]. Melanomas with areas of melanocytoma were also observed, suggesting malignant transformation [ 9 ].…”

Bulbus Destruction by Choroidal Melanocytoma in a Dog: A 3-Year History

“…Choroidal melanocytic tumors are even less malignant (15%) [1]. It is not possible to differentiate melanocytomas from melanomas by clinical signs without histopathological analyses [1,6,18], so enucleation is mostly recommended [8]. Fine needle aspiration of ocular tumors increases the risk of inflammation, infection and hemorrhage [18].…”

“…The risk of a malignant melanoma should be intensely discussed with the owners. Although uveal melanomas rarely metastasize [2,5,6], they have been described in several organs, such as the prostate [22], lungs, lymph nodes, brain, vertebra, kidneys and liver [23]. Metastasis usually occurs via the hematogenous route [18].…”

“…The prognosis for dogs with choroidal melanocytoma is considered good [1], whereas the survival time for dogs with malignant melanomas is significantly shortened [3]. The malignant melanomas do not tend to metastasize [2,5], although occasional reports about metastases exist [6,7]. It is not possible to differentiate melanocytomas from melanomas by clinical signs [1], and histopathological analysis is needed [8].…”

“…Enucleation is mostly recommended when secondary ocular changes appear [4]. Consequently, the literature about choroidal melanocytoma progression over a longer period is scarce [6].…”