Intestinal angioleiomyoma in a dog

Angioleiomyoma is a rare, smooth muscle tumor of vascular origin, which primarily affects the skin. A 9-year-old, castrated male dog presented for transient ataxia. Abnormalities were not detected on physical examination, but blood tests revealed a mild, severely microcytic anemia and transferrin saturation of 2.5% (reference interval, 27%-66%). An exhaustive diagnostic work-up ensued but failed to find the cause of the severe iron deficiency in laboratory, imaging, and endoscopic studies. Severely microcytic anemia had persisted for 6 months, despite iron-dextran injections, and in the absence of clinical signs, until intussusception developed. The abnormal jejunal segment was removed and diagnosed as angioleiomyoma, based on characteristic histological features, positive immunolabeling with α-smooth muscle actin and CD31, and negative S100 and c-Kit/CD117 staining. Hitherto unreported in dogs, intestinal angioleiomyoma was associated with protracted, occult, asymptomatic intestinal blood loss, until intussusception developed. Prognosis appears favorable with full excision, based on clinical behavior in other organs, and the present case.