Amoeboma of the gallbladder mimicking a cholangiocarcinoma: A case report

Amoeboma is a pseudotumoral presentation of amebiasis which is a parasitic infection caused by entamoeba histolytica. Its location in the gallbladder is extremely rare. Indeed, only one other case was found in the literature. Therefore, we present this case report on managing a gallbladder amoeboma mimicking a cholangiocarcinoma.

A 62-year-old presenting for consultation for biliary colic that has been developing for 4 months without associated signs. MRI and thoraco-abdominal CT concluded to a cholangiocarcinoma of the gallbladder extended to the liver with probable localized peritoneal carcinosis. We, therefore, performed extended cholecystectomy with lymphadenectomy for the diagnosis of cholangiocarcinoma. Pathology concluded to an amoeboma of the gallbladder extended to the liver and duodenum.

To our knowledge, there is only one case of gallbladder amoeboma in the literature making this case report valuable. It is important to draw lessons of this observation. Indeed, in front of the discrepancy between the clinic, biology (good general condition and negative tumor markers) and the imaging, we prefer this therapeutic strategy: make a biopsy of the hepatic parenchyma, realize amoebic serology to confirm the diagnosis. Then subject the patient to a therapeutic test based on metronidazole and confirm the disappearance of suspicious lesions by CT scan.

Gallbladder amoeboma is an exceptional entity, but it needs to be kept in mind in case of an atypical presentation of a cholangiocarcinoma. Evoking and confirming the diagnosis preoperatively makes it possible to avoid excessive surgery.