Case report of a spontaneous c-kit positive gastrointestinal stromal tumour in a dwarf Angora rabbit (Oryctolagus cuniculus)

Abstract

A 9-year-old, male dwarf Angora rabbit (Oryctolagus cuniculus), weighing 1.1 kg, was presented to the referring veterinarian with a history of abdominal pain, anorexia and poor body condition. On physical examination, a solid mass was detected in the abdominal cavity by palpation. No other physical abnormalities were apparent at that time. A complete blood cell count revealed a marked hypochromic macrocytic regenerative anaemia and leucopenia with marked lymphopaenia. Serum biochemical analysis showed a marked hypoproteinaemia with hypoalbuminaemia and a moderate increased blood ureic nitrogen concentration. Histopathological evaluation of the intestinal lesion showed a proliferation of spindle cells with morphological features of neoplastic smooth muscle cells which resulted positive for smooth muscle actin, vimentin, desmin, c-kit and faintly positive for cytokeratin (AE1/AE3). Based on histomorphological and immunohistochemical evaluation, a diagnosis of gastrointestinal stromal tumour (GIST) was made. The latter is considered a tumour originating from primitive mesenchymal cells of gastrointestinal tract with pluripotential differentiation. GISTs have been reported in humans, and in a few domestic animal species such as dogs, horses and ferrets. To our best knowledge, this is the first report describing a gastrointestinal stromal tumour in an Angora rabbit. The clinical outcome of GISTs is considered to be similar to other indolent tumours and sarcomas.