Heterotopic pancreas of the gallbladder: A case report of a rare and commonly incidental finding.

Heterotopic pancreas (HP) refers to the presence of ectopic pancreatic tissue located outside of the normal pancreatic location without anatomical or vascular continuity with the pancreas. HP within the gallbladder (HPGB) was first described by Otschkin in 1916. It remains an exceedingly rare pathology with few reported cases. Here we describe a case of HPGB in a 42-year-old female following laparoscopic cholecystectomy for symptoms of biliary colic. She presented with epigastric pain, elevated levels in liver function tests, and gallbladder sludge on ultrasound. Her lipase and bilirubin levels were within normal limits. Histopathological assessment of the gallbladder identified mild chronic cholecystitis and pancreatic heterotopia adjacent to the cystic duct of the gallbladder with all three elements (ducts, acini, and endocrine islets) of the pancreas, consistent with type 1 based on the classification of Gaspar Fuentes et al. HPGB is often diagnosed incidentally during histopathological examination after cholecystectomy. Preoperative diagnosis is challenging due to its rarity. It is thought to be asymptomatic. Although the clinical significance of HPGB remains uncertain, it has been hypothesized that HPGB can cause acalculous cholecystitis and also have the potential for malignant transformation. Our case supports the theory that the exocrine function of an ectopic pancreatic tissue may contribute to chronic inflammation in the gallbladder. In conclusion, although HPGB is a rare finding with unclear clinical relevance, its potential for malignancy and association with cholecystitis warrant further investigation. Given its scarcity, most knowledge about HPGB comes from case reports and case series. This report adds to the existing literature.