Primary intestinal fibrosarcoma caused by intestinal perforation in a dog: a case report

An 11-year-old male Cocker Spaniel was examined for a palpable abdominal mass located in the jejunum after presenting with a history of anorexia and constipation for several weeks. In a contrast radiogram, a structure with well-defined borders adjacent to the intestine was determined. The intestinal mass, measuring 16 × 9.19 × 8.6 cm and weighing 900 g was surgically removed. At gross examination, when the lumen of a portion of the intestine excised together with the tumour mass was exposed, an ulcerated, oval-shaped area 1.2 × 0.6 cm in size was observed on the mucosa. The outer surface of the tumour was homogenous and expanded outwards from the intestinal wall. Histologically, the tumour was composed of fusiform-elongated spindle-shaped to polygonal neoplastic cells forming interlacing fascicles or interwoven bundles in an atypical herringbone pattern. Immnunohistochemically, neoplastic cells stained intensely positive for vimentin, and negative for α-SMA, desmin, cyotokeratin (AE1/AE3), S-100 protein, glial fibrillary acidic protein, neuron specific enolase and synaptophsin. On the basis of the histopathological and immunohistochemical results, the tumour was diagnosed as a fibrosarcoma. The present report is a very rare description of fibrosarcoma of the dog intestine associated with intestinal perforation.