Pancreatic heterotopia mimicking a common bile duct tumor
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A 76-year-old woman presented to our hospital for dull epigastric pain and jaundice for several weeks. High fever obstructive jaundice and elevated lipase levels were detected. Abdominal computed tomography (CT) revealed one 0.5 cm soft tissue nodule in the middle common bile duct (CBD) with arterial-phase hyperenhancement (Fig. 1A). Endoscopic ultrasound (EUS) screening suggested uneven wall thickening of the CBD without channel dilation (Fig. 1B), indicating inflammation or dysplastic changes in the CBD. Following endoscopic retrograde cholangiopancreatography (ERCP) showed one 0.5 cm filling defect in the distal CBD (Supplementary Fig. 1A). Intraductal ultrasonography identified a 0.5 cm intraductal CBD nodule (Fig. 1C) with multiple peri-CBD lymphadenopathies (Fig. 1D). A plastic endoscopic retrograde biliary drainage tube was inserted (Supplementary Fig. 1B), her fever subsided, and jaundice improved.
(A) Abdominal computed tomography demonstrated wall thickening of the common bile duct (CBD) and one 0.5 cm soft tissue nodule in the middle CBD with arterial-phase hyperenhancement. (B) EUS at duodenal bulb showed uneven wall thickening of CBD without channel dilation, indicating inflammation or dysplastic change of the CBD. (C) Intraductal ultrasonography identified the 0.5 cm intraductal CBD nodule at the distal CBD. (D) Intraductal ultrasonography showed multiple peri-CBD lymphadenopathy, and the maximal size of the lymph node was 1.2 cm.
A tissue biopsy during ERCP revealed atypical glands composed of hyperchromatic and pleomorphic tumor cells on a sclerotic fibrous background (Fig. 2A). Immunohistochemically, the tumor was positive for cytokeratin (Fig. 2B), S100P (Fig. 2C), and Ki-67 index (Fig. 2D), suggesting adenocarcinoma.
(A) The tissue biopsy during endoscopic retrograde cholangiopancreatography showed atypical glands composed of hyperchromatic and pleomorphic tumor cells in a sclerotic fibrous background (one 0.5 cm soft tissue nodule in the middle common bile duct [CBD]). Immunohistochemically, the tumor is positive for (B) cytokeratin (uneven wall thickening of CBD without channel dilation), (C) S100P (intraductal CBD nodule at the CBD), and (D) Ki-67 index (multiple peri-CBD lymphadenopathy).
A pylorus-preserving pancreaticoduodenectomy was performed. Grossly, the distal CBD exhibited a stricture with wall thickening and fibrosis over the ampulla of Vater (Fig. 3A). Only cholangitis and a hyperplastic papillary duct were observed in the final CBD pathology (Fig. 3B).
(A) The resected tissue showed distal common bile duct shows stricture with wall thickening and fibrosis over the ampulla of Vater. (B) The histopathology of the pancreatic head showed chronic pancreatitis with hyperplastic papillary duct lesion with atypia.
Pancreatic heterotopia is characterized by the displacement of pancreatic tissues in various parts of the gastrointestinal tract during organogenesis. It can also be found throughout the gastrointestinal tract, as well as in the liver, biliary tree, and gallbladder. Although often asymptomatic, pancreatic heterotopia can cause symptoms depending on its size and location.1 The biliary tract is an extremely rare location for pancreatic heterotopia, and biliary obstruction can occur,2,3 which makes it very challenging to differentiate pancreatic heterotopia from a neoplasm of the bile duct before surgery. Chronic cholangitis causing inflammation can lead to a pathological diagnosis.4 Heterotopic pancreas should be considered in the differential diagnosis of small CBD tumors in patients with chronic pancreatitis and cholangitis. Additional cholangioscopy can be performed before surgery to obtain a more definitive diagnosis. Frequent imaging follow-up schedules can also avoid unnecessary emergent surgeries.
Supplementary Material
Supplementary Fig. 1. (A) Cholangiography of the endoscopic retrograde cholangiopancreatography. (B) An endoscopic retrograde biliary drainage was inserted into the common bile duct.
Supplementary materials related to this article can be found online at https://doi.org/10.5946/ce.2024.196.
Notes
Conflicts of Interest
The authors have no potential conflicts of interest.
Funding
None.
Acknowledgments
The patient’s consent was obtained.
Author Contributions
Conceptualization: HCC; Supervision: PJS; Writing–original draft: HHT, HCC; Writing–review & editing: all authors.