The first case of huge amebic intra-abdominal tumor with asymptomatic amebic colitis

We report a rare case of huge amebic intra-abdominal tumor with asymptomatic amebic colitis. This appears to represent the first report of amebic intra-abdominal tumor. A 31-year-old woman presented to a local doctor with only a sensation of abdominal fullness. Abdominal computed tomography (CT) showed a huge intra-abdominal tumor in the left abdominal cavity, and she was referred to our hospital. Colonofiberscopy for detailed examination showed multiple slight, discrete ulcers in the cecum. Ameboid trophozoites were identified from biopsy specimens, and asymptomatic amebic colitis was diagnosed. Oral metronidazole (MTZ) was administered at 1500 mg/day for 10 days. CT 14 days after starting MTZ showed no change in the intra-abdominal tumor, and resection of the tumor was therefore performed. Pathological examination revealed Entamoeba histolytica with engulfed erythrocytes complicated by hemorrhagic cyst. If an intra-abdominal tumor is present and colitis is observed, amebic intra-abdominal tumor should be considered among the differential diagnoses.