Oral leiomyosarcoma in a woodchuck (Marmota monax) [Oral léiomyome chez une marmotte américaine].

Résumé

We report the case of a 4-year-old female woodchuck (Marmota monax) presented with white, firm and discrete mass in the hard palate. The mass extended into the oral cavity but was well separated from the surrounding tissues. Histology of the tumour showed a malignant mesenchymal tumour with pleomorphic spindle cells varying in differentiation and density. The neoplastic cells had moderate amounts of granular or fibrillar eosinophilic cytoplasm with indistinct cell margins. Nuclei were oval to elongated and frequently blunt-ended with vesicular chromatin. Immunohistochemical study showed that the neoplastic cells expressed vimentin and alpha-smooth muscle actin but did not express desmin, pan-cytokeratin, and S-100. Therefore, histology and immunohistochemistry revealed that the tumour was oral leiomyosarcoma. The oral cavity is an extremely rare site for leiomyosarcoma and the present case is the first report of spontaneous oral leiomyosarcoma in animals.