Fibroma (myxoma) molle in a hamster (Mesocricetus auratus).

An adult female Syrian hamster (Mesocricetus auratus) presented with a large, ulcerated lesion in its right cheek pouch; this wound interfered with the animal's ability to masticate. As a result, the hamster became inappetant and lethargic and lost about 25% of its original body weight within 6 to 9 weeks of presentation. The mass was surgically excised and submitted for histopathological evaluation. Microscopically, the mass was characterized as a neoplastic process partially encapsulated with fibrous connective tissue in the submucosa. Loosely arranged bundles of spindle to stellate cells with round to oval hyperchromatic nuclei and amphophilic cytoplasm were abundant. Some cells had multiple nucleoli, and some mitotic figures were observed. Special stains were used to definitively diagnose fibroma (myxoma) molle, a rare spontaneous neoplastic lesion in the hamster.