嚢胞性胆道閉鎖症：胆道嚢腫を模倣した乳児における診断上の課題

Cystic biliary atresia (CBA) is a rare subtype of biliary atresia (BA), characterised by cystic dilation of the extrahepatic biliary tract. It can radiologically mimic choledochal cysts, often delaying accurate diagnosis and timely management. We report the case of a 2-month-old male infant who presented with cholestatic jaundice and an extrahepatic cystic lesion suggestive of a choledochal cyst. Initial imaging, including magnetic resonance cholangiopancreatography, revealed a cystic structure in the common bile duct. Intraoperative cholangiography demonstrated a dilated extrahepatic biliary tree without contrast passage to the duodenum; intraoperative biliary exploration confirmed distal ductal obliteration, consistent with CBA with intact proximal ducts. A laparoscopic hepaticoduodenostomy was initially performed; however, due to persistent bile leak and intra-abdominal collection, conversion to open Roux-en-Y hepaticojejunostomy was required. Histopathology confirmed the diagnosis of BA. This case underscores the importance of maintaining a high index of suspicion for CBA in neonates with cystic biliary lesions and highlights the role of intraoperative findings in guiding definitive surgical management.