Background: The presence of congenital anatomic abnormalities (CAA) can alter the surgical techniques of management of hepato-pancreato-biliary (HPB) malignancy. We describe five such cases and discuss the surgical approaches utilized. Methods: We performed a retrospective review of our prospectively acquired HPB surgery database from 11/28/2005 to the present to identify all cases of CAA associated with HPB malignancy. Results: We identified 5 cases of CAA out of a total of 659 HPB cases reviewed (.8%). One case of retroperitoneal transverse colon and two cases each of dorsal agenesis of the pancreas and intestinal malrotation were identified. The case of retroperitoneal transverse colon occurred in a patient requiring pancreaticoduodenectomy (PD) for pancreatic adenocarcinoma (PA). The transverse colon lay dorsal to the superior mesenteric artery and vein, and the duodenum lay ventral to the mesenteric vessels. A classic PD was performed and the reconstruction was altered by bringing the jejunal limb up in an antecolic fashion. The two cases of dorsal agenesis of the pancreas were identified in patients with PA. These patients lacked development of the body and tail segments of the pancreas. A pylorus preserving total pancreatectomy was performed in both cases. Patients were managed postoperatively with intravenous insulin infusion and discharged home on insulin. In the two cases of malrotation, the colon was noted to be on the left side of the abdomen and the small intestine on the right. One patient underwent extrahepatic bile duct resection for hilar cholangiocarcinoma. The second patient was found to have locally advanced PA encasing the superior mesenteric artery and underwent palliative bypass. In both cases, Roux en Y hepaticojejunostomies were performed in a right paracolic position. Mean operative time, blood loss, length of postoperative hospital stay, and complications were not significantly different from patients undergoing standard PD and liver resection. The four patients who underwent resection of their malignancies had negative surgical margins and are currently all alive at a mean followup of 12.4 months. Conclusion: In experienced hands, rarely encountered congenital anatomic abnormalities found in association with HPB malignancy do not preclude safe surgical resection.
Table 1.

ANOMALY	PROCEDURE	EBL (ml)	POSITION OF JEJUNAL LIMB	PATHOLOGY/MARGINS	LENGTH OF STAY (Days)	COMPLICATIONS	Follow Up (Months)
RETROPERITONEAL TRANSVERSE COLON	Classic Pancreaticoduodenectomy	500	Antecolic	-Moderately Differentiated Pancreatic Adenocarcinoma-Margins (-)	6	None	17.3
DORSAL AGENESIS OF PANCREAS	Total Pancreatectomy	500	Retrocolic	-Moderately Differentiated Pancreatic Adenocarcinoma-Margins (-)	10	Ileus	13.0
DORSAL AGENESIS OF PANCREAS	Total Pancreatectomy	250	Retrocolic	Pancreatic Adenocarcinoma -Margins (-)	6	None	1.0
MALROTATION	Extrahepatic Bile Duct Resection	100	Right Paracolic	-Poorly Differentiated Cholangiocarcinoma-Margins (-)	15	Ileus	8.0
MALROTATION	Palliative Hepaticojejunostomyand Gastrojejunostomy	500	Right Paracolic	-Moderately Differentiated Pancreatic Adenocarcinoma -Unresectable	5	None	5.7