Polycystic hepatic disease, thoracic granular cell tumor and secondary hypertrophic osteopathy in a horse.

A 13-year-old American Saddlebred mare was presented with a 4-day history of anorexia. Physical examination revealed increased inspiratory effort and bony enlargement of the distal limbs. Radiographs indicated a thoracic mass and periosteal proliferations on the distal limbs consistent with hypertrophic osteopathy. Gastric endoscopy revealed distal esophageal and gastric ulceration, and functional pyloric stenosis. Abdominal ultrasonographic examination revealed multiple large, cystic structures associated with the liver. A percutaneous biopsy indicated the thoracic mass to be a granular cell tumor. At necropsy, a large mass consisting of intercommunicating cystic structures was present confluent with the right caudal edge of the liver. Histologically these hepatic lesions were consistent with cystic hepatic disease, which has not previously been reported in the horse.