Amebiasis Elsewhere in the Gastrointestinal Tract

Esophagus. Direct involvement of the esophagus is extremely rare, but has occurred as a result of spread from a periesophageal abscess; clinically the patient may have dysphagia and pain. More important, obstruction and displacement of the esophagus from enlargement of the liver are recorded, presenting as dysphagia. In such patients, the hemidiaphragm (usually the left) is raised and fluoroscopy, or preferably ultrasound where available, shows reduced movement; a pleural effusion, with or without a pericardial effusion, is likely. Barium swallow shows the esophagus is compressed and usually displaced posteriorly by the mass under the diaphragm. There is also lateral displacement, the direction depending on the location of the amebic abscess, whether in the left or right lobe of the liver. Typically, the lower end of the esophagus is rotated around the enlarged liver and the stomach is also displaced.

The differential diagnosis includes achalasia and esophageal carcinoma. The esophagus does not dilate to the same extent as in achalasia and restricted diaphragmatic movement suggests a subphrenic lesion. There should be no intrinsic mass within the esophagus in these amebic patients.

Stomach. Primary amebiasis of the stomach has not been recorded. An enlarged liver, however, can displace the stomach. Occasionally, an abscess in the left lobe of the liver can rupture into the stomach and, if the abscess also involves the diaphragm and pericardium, a pneumothorax or pneumopericardium may result (see Figs. 1.85 and 1.101).

Duodenum. Edema of the duodenal loop can be demonstrated in some patients with amebiasis. The duodenum may become atonic and mildly dilated, and the mucosa is swollen and edematous, with spiking of the folds. Similar changes are found in other parasitic infections of the small bowel (e.g., giardiasis and strongyloidiasis) and there may be no distinguishing features. Such findings, associated with vague dyspeptic symptoms without demonstration of an ulcer, should suggest the possibility of parasitic infection, including amebiasis. The duodenal C-loop can be involved with inflammatory changes secondary to a pericolic abscess originating from amebic colitis in the adjacent transverse colon.

Small Bowel. Amebiasis does not affect the terminal ileum as an isolated finding, but will do so in 10% or more of patients where there is cecal involvement. Mucosal thickening, pseudopolyps, rigidity, and ulceration may be found. An ameboma of the ileum is recorded. An important distinguishing feature among amebiasis, Crohn's disease and tuberculosis in the ileocecal area is the high incidence of involvement of the ileum in the latter two diseases when the right colon is affected.

Gallbladder. Primary involvement of the gallbladder is not recognized, but an amebic liver abscess may cause oral cholecystography to be unsuccessful.