AT THE FOCAL POINT

Lawrence J. Brandt, MD, Associate Editor for Focal Points

Ameboma mimicking colon cancer

A 45-year-old man was referred to our endoscopy centerbecause of hematochezia and abdominal pain; fecal occultblood test results were positive. He had no personal or fam-ily history of inflammatory bowel disease or colon cancer,but he was homosexual. Laboratory data, including anti-HIV antibody and tumor markers, did not demonstrateany abnormal findings. Bacterial culture showed normalbacterial flora. Colonoscopy with indigo carmine dye spray-ing showed a large ulcerative lesion in the cecum with ele-vated margins suggesting colonic cancer with submucosalinvasion (A, B). Histology demonstrated surface exudatesshowing trophozoites of Entamoeba histolytica with scat-tered ingested erythrocytes; no malignant cells were evi-dent (C, periodic acid-Schiff, orig. mag. �200). A serumanti-amoebic antibody was positive. A diagnosis of ame-

www.giejournal.org Volume 69,

boma was made. Metronidazole was given for 14 days ata dose of 1500 mg per day, with subsidence of symptoms.Twenty days after treatment, repeat colonoscopy demon-strated only an ulcerative scar in the cecum (D).

DISCLOSURE

All authors disclosed no financial relationships rele-vant to this publication.

Takashi Abe, MD, Naoki Kawai, MD, Masakazu Yasumaru,MD, Masayo Mizutani, MD, Hiroki Akamatsu, MD, Endos-copy Center; Shigeki Fujita, MD, Department of Pathology,

No. 3 : Part 2 of 2 : 2009 GASTROINTESTINAL ENDOSCOPY 757

At the Focal Point

Osaka Police Hospital, Osaka; Tsutomu Nishida, MD, HidekiIijima, MD, Masahiko Tsujii, MD, Department of Gastroen-terology and Hepatology, Osaka University Graduate School

Air under the right diaphragm: colsyndrome

758 GASTROINTESTINAL ENDOSCOPY Volume 69, No. 3 : Part 2 of

of Medicine, Osaka; Masahiko Tsujimoto, MD, Departmentof Pathology, Osaka Police Hospital, Osaka, Japan

doi:10.1016/j.gie.2008.12.065

CommentaryNot as clearly distinguishable by color as the Four Horsemen of the Apocalypse (white [Conquest], red [War], black [Pesti-lence], and pale green [Death]), the four horsemen of the cecum (carcinoma, lymphoma, tuberculoma, and amoeba) inthis case were distinguished by indigo cyanine green staining and biopsy. All large and ulcerated masses of the cecummay be either malignant or infectious, their relative frequencies in large measure determined by geography, genes, and be-havior. Geography and behavior here suggest ameboma, although suggestion is not sufficient for therapeutic action. Sexualtransmission of amebiasis among anoreceptive men has been well documented, especially among those who have multiplepartners. Invasive amebiasis, however, is no more frequent in patients with AIDS than in healthy controls. Fortunately, of the 9species of amoebae that can infect man, only one, E histolytica, is undisputedly pathogenic. In this patient, histology revealedthe pathognomonic characteristic of this species, namely erythrophagocytosis. This case would seem to have a happy ending,but as Orsen Welles said, ‘‘that, of course, depends on where you stop your story.’’

Lawrence J. Brandt, MDAssociate Editor for Focal Points

onoscopy in the setting of Chilaiditi

2 : 2009 www.giejournal.org