Epibulbar melanoma in a foal |
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Authors: | Richard J McMullen Alison B Clode Arun Kumar R Pandiri† David E Malarkey‡ Tammy Miller Michau Brian C Gilger |
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Institution: | Department of Clinical Sciences;, Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC;;and Cellular and Molecular Pathology Branch, National Institute of Environmental Sciences, Research Triangle Park, NC |
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Abstract: | A case of epibulbar melanoma in a 6-month-old, gelded, chestnut Hanoverian foal is reported. The location and clinical appearance upon initial presentation led to the tentative diagnosis of staphyloma or a congenital mass of unknown origin. An attempt was made to surgically excise the mass under general anesthesia, but due to its infiltrative nature and intraoperative appearance, most, but not all was removed without compromising the integrity of the globe. Histopathological evaluation revealed a multinodular to packeted, poorly demarcated, unencapsulated, infiltrative exophytic melanocytic neoplasm composed of bundles and nests of plump spindloid to polygonal heavily pigmented epithelioid neoplastic cells interspersed with pigment-laden macrophages within a fine fibrovascular stroma. Upon examination after enucleation, neoplastic cells were found to infiltrate into the lateral cornea, sclera and the choroid. This is a unique case of an epibulbar melanoma with choroidal invasion in a foal. Based on the sudden onset and rapid growth as well as the histological evidence of invasion, well-differentiated features, heavy pigmentation, and no apparent mitoses, this neoplasm was considered to be a low-grade malignant melanoma. At 14 months after excision there is no evidence of recurrence. |
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Keywords: | congenital epibulbar equine melanoma neoplasia |
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