Equine Primary Liver Tumors: A Case Series and Review of the Literature

Abstract

Abstract. Hepatoblastoma (HB) is an uncommon pediatric liver tumor in humans and horses. In humans, HB is most frequently diagnosed in fetuses, neonates, and young children, whereas hepatocellular carcinoma (HCC) affects juvenile and adult humans. Hepatoblastoma in the horse is rare, with only 9 reported cases. Affected horses ranged in age from late-term aborted fetuses to 3 years. The current study describes 3 new cases of primary liver tumors in horses and reviews findings in relation to other reports on this condition. Tumors classified as HB were identified in a male Standardbred aborted fetus and in a 4-year-old Thoroughbred filly. Hepatocellular carcinoma was diagnosed in a 15-month-old Paint filly. In the Standardbred fetus, the tumor was only present in the liver. In the Thoroughbred and Paint fillies, primary tumors were in the right liver lobe and at the hilus, respectively, and there were metastases to other lobes (HB) and mesenteric lymph nodes (HCC). Tumors were sharply demarcated from adjacent tissue, nonencapsulated, compressive, and invasive. Consisting of cords and nests, or disorganized sheets of epithelial cells, tumors had variable stromal and vascular components. The fetal tumor contained areas of smaller, less differentiated cells with a pronounced mesenchymal component interpreted to be embryonal hepatic tissue. Diagnoses were based on tumor histomorphologic features, resemblance to hepatocyte developmental stages, age of the animal, and patterns of metastasis. Tumors classified as HB were a-fetoprotein immunoreactive. Primary hepatic tumors in the horse are diverse in morphology and include subtypes compatible with classification criteria applied to human tumors.

Imaging Diagnosis—hypoglycemia Associated With Cholangiocarcinoma and Peritoneal Carcinomatosis in a Horse

“…3,4 Mixed hamartoma, mesenchymal hamartoma, and hepatocellular carcinoma have been reported in fetuses and juvenile horses. 3 While horses with hepatic tumors may have nonspecific clinical signs such as weight loss, colic, inappetence, and lethargy, the unique feature of this report was the clinical presentation of weakness, ataxia, head pressing, and seizure activity associated with hypoglycemia. 4 Clinically apparent hypoglycemia is rare in adult horses, and unlike most other species of domestic animals, no specifically reported condition is commonly associated with hypoglycemia in the adult horse.…”

Neoplasia in 125 donkeys (Equus asinus)

“…22 We observed only a single hepatic neoplasm and a suspected metastatic pancreatic neoplasm with carcinomatosis. Primary hepatic and pancreatic tumors are very rare in both horses 3 and donkeys. 26,35,46 A retrospective analysis of geriatric U.K. donkeys reported benign (biliary adenoma, cystadenoma, and cholangioma) and malignant (cholangiosarcoma and bile duct carcinoma) liver neoplasia at 0.7% and 4.2% of diagnoses, respectively.…”

Hämoperitoneum beim Pferd

“…Eine Vielzahl sich im Bauchraum befindlicher Neoplasien wurde bereits als Ursache eines Hämoperitoneums beschrieben [3,5,7,11,19], z. B.:…”