Cecal ameboma.

摘要

A 45-year-old man presented with right lower abdominal pain and mild diarrhea of 2 weeks' duration. He also noticed red blood coating his stools on several occasions before coming to our clinic. Laboratory data, including antihuman immunodeficiency virus antibody and tumor markers, revealed no abnormal findings. A smear and a culture of his stools were negative for bacterial pathogen and Entamoeba histolytica. Colonoscopy, with indigo carmine dye spraying, showed a large ulcerative lesion with marginal elevation in the cecum and several erosions in the rectum. This colonoscopic appearance observed in the cecum was suggestive of a nonpolypoid-growth-type coloniccancer with submucosal invasion, metastatic colonic cancer, or malignant lymphoma as a differential diagnosis. Biopsy specimens obtained from the ulcerative lesion in the cecum revealed a number of amebic organisms, trophozoites(C; H&E, orig. mag. x400). A serologic test for amebiasis performed 7 days after his colonoscopic examination was positive, at 1:100. A diagnosis of cecal ameboma was made. After treatment with metronidazole, his symptoms rapidly subsided. At 35 days after the treatment, colonoscopic examination, with indigo carmine dye spraying, revealed the disappearance of the ulcerative lesion in the cecum.