Distal cholangiocarcinoma in a patient with portal annular pancreas and aberrant common hepatic artery: a case report

Background Portal annular pancreas (PAP) is a rare congenital anatomical variation characterized by pancreatic parenchyma encircling the portal vein (PV) or superior mesenteric vein (SMV). An aberrant common hepatic artery (CHA) originating from the superior mesenteric artery (SMA) represents another uncommon vascular anomaly. The coexistence of these two variations with a distal common bile duct (CBD) malignancy is extremely rare and poses significant technical challenges for pancreaticoduodenectomy (PD). Case presentation We report a case of a 55-year-old male with obstructive jaundice caused by distal cholangiocarcinoma, concurrent with PAP (Joseph Type IIIb) and a CHA arising from the SMA (Michels type IX). Preoperative imaging, including multiphasic contrast-enhanced computed tomography (CT) with arterial and portal venous phase protocols and three-dimensional vascular reconstruction, meticulously delineated the complex anatomy—including the complete course of the aberrant CHA, the origin of the gastroduodenal artery (GDA), the relationship of the CHA to the pancreas, PV, and CBD, and the main pancreatic duct (MPD) coursing anterior to the PV. A classical pancreaticoduodenectomy (Whipple procedure) was successfully performed. Key surgical adaptations included a phased pancreatic transection strategy to address the annular pancreas—creating two transection surfaces with en bloc resection of the posterior pancreatic tissue—and careful dissection to preserve the aberrant hepatic artery. The patient recovered uneventfully with only a biochemical leak and without clinically relevant postoperative pancreatic fistula (POPF, Grade B/C), delayed gastric emptying, post-pancreatectomy hemorrhage, or bile leakage. Conclusion This case underscores the critical importance of detailed preoperative radiological evaluation in identifying complex anatomical variations. Individualized surgical planning, guided by precise anatomical understanding, is paramount for safe and successful PD in such challenging scenarios. A literature review contextualizes the anatomical features, surgical risks, and management strategies for this rare combination.