Giant Hepatobiliary Cystadenoma Requiring Biliary Reconstruction in a Cat: A Case Report

BACKGROUND: Hepatobiliary cystadenoma is an uncommon benign biliary tumour in domestic cats (Felis catus) that may mimic cystadenocarcinoma. Although imaging provides important diagnostic information, histopathological examination is required for confirmation. This case was notable for the exceptionally large lesion and the need for biliary reconstruction following surgical excision. CASE PRESENTATION: A 7-year-old neutered male domestic shorthair cat weighing 8 kg was presented with several weeks of vomiting, inappetence and abdominal distension. Serum biochemistry demonstrated a cholestatic pattern with increased alkaline phosphatase and gamma-glutamyl transferase activities. Abdominal radiographs revealed a cranial abdominal mass, and ultrasonography identified a multiloculated cyst with thin septa and no mural nodules. Contrast-enhanced computed tomography confirmed a 163 × 148 × 136 mm cystic hepatic mass with homogeneous fluid attenuation, non-enhancing septa and no solid components. Exploratory laparotomy enabled complete excision with preservation of hepatic tissue. Partial resection of the common bile duct followed by end-to-end anastomosis was performed to restore bile flow. Histopathological examination confirmed hepatobiliary cystadenoma. Recovery was uncomplicated, and at the 3-month follow-up the cat was clinically normal, with no ultrasonographic evidence of recurrence. CONCLUSIONS: Large multiloculated hepatic cystic lesions with homogeneous fluid contents and no enhancing mural nodules should prompt consideration of hepatobiliary cystadenoma in cats. Complete surgical excision with preservation or reconstruction of biliary structures may result in a favourable short-term outcome. Longer clinical, biochemical, and imaging follow-up is recommended.