Sclerosing eosinophilic extrahepatic cholangitis in a cat

A 9-year-old female cat was presented to the veterinary hospital with a history of progressive weight loss, anorexia and jaundice. Clinical findings included poor body condition, hypothermia and jaundice. The ultrasound findings were consistent with cholangiohepatitis associated with pancreatitis and the biochemical tests indicated a marked increase in activities of hepatobiliary enzymes (alkaline phosphatase, alanine aminotransferase, gamma-glutamyl transpeptidase). At necropsy, the animal had marked jaundice in the mucous membranes and subcutaneous tissue and a mildly enlarged liver with diffusely orange discolouration. The cystic duct was thickened, white, firm and completely obstructed. The gallbladder was enlarged and contained thickened bile. Microscopically, the cystic duct was obliterated by severe proliferation of fibrous connective tissue and marked proliferation of bile ducts, with a prominent multifocal inflammatory cell infiltrate composed predominantly of eosinophils, lymphocytes, rare plasma cells and macrophages. Although eosinophilic cholangitis is considered benign in humans, in this case it had led to complete obstruction of the cystic duct due to wall thickening caused by eosinophilic inflammation and fibrous connective tissue proliferation, which contributed to clinical deterioration.