Combined Pancreatic and Gastric Heterotopia Presenting as a Gallbladder Mass: An Under-Recognized Cause of Post-Prandial Right Upper Quadrant Pain

Abstract

Pancreatic and gastric heterotopias are defined as pancreatic and gastric tissue located outside their anatomic location without vascular or anatomical continuity with the pancreas proper or the stomach. These heterotopias have been described in the esophagus, stomach, and Meckel's diverticulum, however their presence in the gallbladder is rare. Heterotopias in the gallbladder can present with symptoms of acute and chronic cholecystitis, and perforation. We report a case of an 18-year-old female with polypoid gastric and pancreatic heterotopia and focal intestinal metaplasia of the gallbladder with clinical suspicion of acute cholecystitis. An 18-year-old woman presented with several years of nausea, non-biliary emesis and right upper quadrant pain. Her symptoms were most noticeable post prandial after a high fat meal. She was treated symptomatically for years with ondansetron, promethazine, NSAIDs, and sucralfate without relief. She denied any past medical or surgical history. A previous EGD was unremarkable and biopsies of the stomach and duodenum were negative for metaplasia and dysplasia. A right upper quadrant ultrasound showed a 9.6 mm polyp without sludge or stones. Cholecystectomy was performed and gross specimen showed a 0.9 x 0.7 x 0.6 cm rubbery pink polypoid nodule. Pathology revealed polyploid gastric and pancreatic heterotopia with focal intestinal metaplasia. There was no dysplasia and immunohistochemical stain for helicobacter pylori was negative. Mild chronic cholecystitis and cholesterolosis were present. The incidence of heterotopic pancreatic and gastric tissues ranges from 0.1 to 13 percent in the general population. Though the etiology is no yet well defined, theories suggest it results from an error during embryological development during rotation of the foregut. Acquired forms of heterotopia have been described, particularly gastric metaplasia. Though usually benign, malignant transformation can occur. Heterotopic pancreatic and gastric heterotopia in the gallbladder is difficult to diagnose preoperatively and is usually confirmed by histopathologic examination of the surgically resected specimen. Because pancreatic and gastric heterotopia is rare and often accompanied with nonspecific symptoms, delay in diagnosis occurs. In addition, awareness of this under reported condition by pathologist is important for its identification because should not be diagnosed as neoplastic disease, such as adenoma.Figure: Histology of the gallbladder mass showing combined pancreatic and gastric heterotopia with H&E stain at 20x magnification.Figure: Histology of the gallbladder mass showing combined pancreatic and gastric heterotopia with H&E stain at 400x magnification.Figure: Histology of the gallbladder mass showing combined pancreatic and gastric heterotopia with H&E stain at 400x magnification.