engleski

METASTATIC SPREAD OF CANINE PERIANAL MELANOMA - A CASE REPORT

Melanocytic tumors are relatively frequent tumors of the skin and oral cavity in older dogs, and their biological behaviour often depends on its location. Oral tumors, including mucocutaneous tumors of oral cavity, are mostly malignant contrary to skin tumors which are usually benign. Perianal melanoma, although mucocutaneous, has still unknown prognosis due to rarity of this tumor in dogs. This report describes a case of a 13 year old mixed breed bitch. The animal had a perianal nodular mass and the excisional biopsy was preformed. The tumor was diagnosed as melanocytoma. Two years later, locally recurrent mass was found with constipation as only clinical sign. By the fine-needle aspiration and cytological analysis of the mass diagnosis of suspected melanoma was made. The dog was euthanized and the necropsy showed perianal exophytic black nodule. Also, a large mass in subsacral area of the pelvic cavity was revealed. Multiple tumor nodules were found at the serosal surfaces of stomach, gallbladder, rectum, urinary bladder and omentum. Likewise, lung metastases were found. The diagnosis of perianal melanoma with metastatic spread was made by histopathological examination. Immunohistochemical staining for Melan A and Ki-67 was performed, both on initial melanocytoma and subsequent melanoma, retrospectively, to determine the possibility of malignant transformation of this tumor. To our knowledge this is a first necropsy report of metastatic spread of canine perianal melanoma. Thus, this case presents the malignant behaviour of a melanoma located at an unusual location for dogs, similary to such tumors in humans.

perianal melanoma, metastases, dog

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