Invasive cholangiocarcinoma identified in congenital biliary dilatation in a 3-year-old boy.

We herein report a 3-year-old male demonstrating invasive cholangiocarcinoma (CC) associated with congenital biliary dilatation (CBD). A 3-year-old Japanese boy was admitted to our hospital with abdominal pain and vomiting. Computed tomography and magnetic resonance imaging demonstrated a dilated extrahepatic bile duct. A diagnosis of Todani's type 1a CBD was made. Intraoperative cholangiography demonstrated the presence of pancreaticobiliary maljunction but could not reveal any tumor lesion in the bile duct. The excision of extrahepatic bile duct and gallbladder and Roux-en-Y hepaticojejunostomy were performed. On gross inspection, we could not find any tumor lesion in the resected specimen. However, the postoperative histopathologic examinations confirmed the presence of well-differentiated tubular adenocarcinoma with lymphovascular invasion. Most of the carcinoma remained within the mucosal layer, and the carcinoma was identified at both the distal and proximal surgical margins of the bile duct. We scheduled additional surgery to eradicate the residual carcinoma, but informed consent for the extra surgery could not be obtained. A close follow-up with abdominal computed tomography has been going on without either additional surgery or adjuvant chemotherapy about for 1 year. The patient has so far been clinically doing well without any obvious symptoms of recurrent disease. To our knowledge, this report is the youngest case of CC associated with CBD.