Heterotopic gastric mucosa in gallbladder-A rare differential diagnosis to gallbladder masses: A systematic review.

Background: Heterotopic gastric tissue can be found in the entire gastrointestinal tract. It is usually located in the upper intestine. Rarely, it can be found in the gallbladder. This study describes several clinically, imaging features as well as histopathology findings of heterotopic gastric tissue in gallbladder (HGM).

Methods: The radiologic database of 1 tertiary university hospital was retrospectively screened for HGM. Additionally, a systemic review of the Medline database was conducted to identify previously published cases reports. In all cases clinical, imaging as well as histopathology features were retrieved from the papers.

Results: In our databases, 1 patient with HGM was identified. Additionally, the systemic review yielded 32 suitable papers with 34 patients. Clinically, most of the patients suffered from abdominal discomfort. Most of the lesions were located in the lower gallbladder, especially (n = 14, 40%) in the gallbladder neck. On sonography, in 20.7% a broad-based mass was described. In 10.3% a sessile polyp was identified. In 5 cases, the mass was characterized as hyperechoic (55.5%), as isoechoic in 3 (33.3%) cases, and hypoechoic in 1 (11.1%). On computed tomography (CT), the lesions were most frequently hyperdense and all of them showed a slightly enhancement after application of contrast medium. On histopathology, most cases revealed heterotopic gastric mucosa of body-fundic type (60%) with chief and parietal cells, followed by pyloric type glands (20%). Every patient was treated with cholecystectomy and all had an uneventful recovery.

Conclusion: HGM is a rare disorder with several differential diagnoses. Typically features were described to identify HGM in clinical routine and rule out malignant diseases like gallbladder carcinoma.