A Himalayan Rex guinea pig was presented with a history of nodular, partially ulcerated masses in the subcutis of the left shoulder. Histological examination revealed a garland-like to nodular, infiltrative neoplastic mass of the epidermis and hair follicle epithelium, which obscured the dermoepidermal junction. Neoplastic cells were immunopositive for S100, PNL-2, vimentin and melan-A antigens. No immunolabelling of CD3, CD79, Iba-1 or pancytokeratin was observed. This is the first detailed description of spontaneous amelanotic malignant melanoma in this species.

中文翻译：

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喜马拉雅雷克斯豚鼠（Cavia porcellus）的黑色素恶性黑色素瘤

一只喜马拉雅雷克斯豚鼠的左肩皮下组织有结节性、部分溃疡肿块。组织学检查显示表皮和毛囊上皮的花环样至结节性浸润性肿瘤块，掩盖了真皮表皮交界处。肿瘤细胞对 S100、PNL-2、波形蛋白和黑色素 A 抗原呈免疫阳性。没有观察到 CD3、CD79、Iba-1 或全细胞角蛋白的免疫标记。这是对该物种自发性无色素沉着性恶性黑色素瘤的首次详细描述。