Canine low-grade intra-orbital myxosarcoma: case report.

OBJECTIVE The aim of this study was to evaluate important clinical, morphological, histopathological, histochemical, and immunohistochemical characteristics in order to establish the diagnosis and prognosis of a low-grade intra-orbital myxosarcoma. ANIMAL STUDIED A mongrel dog presented a 2-year history of a neoplastic mass behind the right eye. RESULTS The neoplasm presented a mesenchymal spindle and stellate cell proliferation with an abundant myxoid matrix, moderate anisocariosis, and a low mitotic index. It stained positive for vimentin, moderately positive for periodic acid-Schiff, and negative for Gomori trichrome stain and α-smooth muscle actin. CONCLUSIONS One year following surgical excision, the patient remains disease free. The histological findings established a diagnosis of a rare canine intra-orbital low-grade myxosarcoma.

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