A Case of Acute Cholecystitis Caused by a Incarcerational Hyperplasic Polyp

The patient was a 52-year-old man who visited our hospital with the chief complaints of fever, abdominal pain and vomiting. Blood examinations revealed a marked increase in acute-phase reactants and increase in the biliary enzyme levels, and abdominal ultrasonography revealed gallbladder enlargement and gallbladder wall thickening. Plain abdominal computed tomography revealed a cystic lesion with an isodensity contour and low-density center, measuring approximately 2.0 cm in diameter, in the neck of the gallbladder. Based on these findings, acute cholecystitis due to a cystic lesion in the neck of the gallbladder was diagnosed. Because the inflammation was severe, emergency percutaneous transhepatic gallbladder drainage (PTGBD) was performed. The lesion was found to be a pedunculated tumor with a smooth surface by PTGBD imaging, and to be multilocular with a uniformly thickened wall by magnetic resonance imaging. Thus, we suspected a multilocular cystic benign tumor, and performed laparoscopic cholecystectomy. Examination of the resected specimen revealed that the tumor was pale red in color and pedunculated, with a smooth surface, and the histopathological findings were consistent with the diagnosis of a hyperplastic polyp of the metaplastic epithelial type. Acute cholecystitis due to incarceration of a hyperplastic polyp is rare. Therefore, we report our case as the first such case reported from Japan.