Solitary Biliary Hamartoma with Cholelithiasis in a Domestic Rabbit (Oryctolagus cuniculus)

Abstract

Abstract. Hamartomas of the liver and biliary system are extremely rare entities in both animals and humans. Biliary hamartomas in humans are usually multiple and constitute the von Meyenburg complexes. This report describes the presence of a large solitary mass arising from the edge of the right medial liver lobe of a domestic rabbit. Histologically, the mass was composed of an extensive network of large varying sized cystic structures lined by simple cuboidal to columnar epithelium within an abundant fibrous stroma. Within many of the cyst lumina were varying sized, pale white to greenish hard concretions identified as choleliths and were analyzed and found to be composed of calcium carbonate. This is the first known report of biliary hamartoma with cholelithiasis in rabbits.Key words: Biliary; hamartoma; liver; Oryctolagus; rabbits.Hamartomas are defined as focal malformations that are composed of an abnormal mixture of tissue elements or an abnormal proportion of a single element, normally present at that site. 26 Hamartomas have been described in a number of organ systems, including the liver and associated biliary tract of animals and humans. In humans, mesenchymal hamartomas of the liver, composed of well-vascularized mature connective tissue intermixed with elongated branching bile ducts and hepatocytes, have been described.2 A bile-duct hamartoma, also known as von Meyenburg complex in humans, is composed of a multiple, varying sized, focal disorderly collection of bile ducts and ductules surrounded by abundant fibrous stroma, and scattered throughout the hepatic parenchyma of numerous lobes. 2In this report, a solitary large biliary hamartoma with cholelithiasis in a domestic rabbit is described.A recently euthanized adult male intact transgenic LCAT (lecithin : cholesterol acyltransferase) New Zealand white rabbit was presented to the diagnostic pathology services branch of the Division of Veterinary Resources at the National Institutes of Health in Bethesda, Maryland. Before submission, the animal had been demonstrating ataxia and incoordination of 1 month's duration. Because of progression of the clinical signs, the animal was humanely euthanized. On necropsy, the animal was in fair nutritional condition. Upon opening the peritoneal cavity, an approximately 4 3 2 3 1-cm irregularly shaped mass was adhered by fibrous connective tissue to the caudal extent of the right medial liver lobe and partially adhered by fibrous adhesions to the cranial pole of the right kidney. The proximal 25% of the mass closely adhered to the liver was greenish blue, whereas the remaining mass was opaque whitishtan. The surface of the mass was gyrose (Fig. 1). The mass was teased away from the liver, at which point a vascular or biliary communication between the liver lobe and the mass was not observed. The mass was easily removed from the renal capsule. Upon cutting into the mass, hard gritty concretions were present. Upon further evaluation, it was noted that the gyrose sections were elongate cystic structures in which th...

Biliary cystadenoma in a male domestic Dutch rabbit (Oryctolagus cuniculus)

“…One biliary hamartoma has been reported attached to the capsular surface of a liver lobe in a rabbit and the histological features, including concretion material within cystic spaces, seemed similar to this case (Starost 2007). That animal was an experimental subject euthanased without treatment.…”

Respiratory Epithelial Adenomatoid Hamartoma in a Dog

“…4 In animals, vascular, 8,9,11 rectal, 5 cranial nerve, 11 meningeal, 7 muscle, 8 melanocyte, 8 bile duct, 13 ovarian interstitial cell, 6 cutaneous adnexal, 8 mesenchymal, 2 pulmonary microcytic, 14 hypothalamic, 3 and fibroepithelial 12 hamartomas have been reported. However, no nasal or frontal sinus hamartomas have been reported in animals.…”

Extrahepatic biliary tract pathologies in mammalian species of zoo animals and wildlife: a review

“…Trematode infestation represents the single pathology reported for free-ranging Lagomorpha species. With respect to reports on domestic rabbits [DeCubellis et al, 2010;Hofmann et al, 1968;Starost, 2007], cholelithiasis as well as neoplasia can be expected to occur in Lagomorpha. The lack of corresponding reports might be mainly due to limited investigation conducted yet and the presumably low average life expectancy of freeranging individuals.…”