Gastrointestinal Malakoplakia

Abstract

Malakoplakia is an inflammatory process related to defective macrophage response to bacterial infection. To further characterize the clinicopathologic manifestations of gastrointestinal malakoplakia, 26 cases were identified from 6 institutions. Hematoxylin and eosin-stained slides and available stains were reviewed, and pertinent clinicopathologic features analyzed. Sixteen patients were women (62%). Mean patient age was 64 (range: 24 to 83). Sites included the colorectum (n=23), appendix (n=1), and stomach (n=2). Clinical indications for tissue procurement included screening (n=14), tumor resection (n=5), diarrhea (n=1), adenoma surveillance (n=1), ulcerative colitis flare (n=1), abdominal pain (n=1), and appendicitis (1). All cases featured histiocytes with abundant, pale, eosinophilic cytoplasm focally containing Michaelis-Gutmann bodies. The process frequently involved the mucosa (n=19), with architectural distortion in 13 cases. Lymphoid aggregates were present in 18 cases, which were prominent or obscuring in 11 (all colon biopsies) and provoked concern for lymphoma in 2. Associated findings included adenocarcinoma (n=5), adenoma (n=2), gastric hyperplastic polyps (n=1), chemical gastritis (n=1), collagenous colitis (n=1), and active chronic colitis (n=2). In cases with available stains, Michaelis-Gutman bodies were highlighted by Periodic Acid-Schiff with diastase, Von Kossa, and iron stains. Although 2 cases were positive for Tropheryma whipplei antibody, no T. whipplei transcripts were detected on real-time polymerase chain reaction. All patients with available follow-up are alive and well with no additional instances of malakoplakia. Malakoplakia of the gastrointestinal tract is a benign, incidental finding. Although histologic features in the stomach and colon resections are similar to those at other sites, exuberant lymphocytic response in colon biopsies and immunoreactivity with T. whippleii antibody may provoke initial confusion and lead to unnecessary time and resource investment.

Malakoplakia mimicking a locally advanced colorectal neoplasm

“…Interestingly, colorectal cancer was simultaneously diagnosed in 19% of the patients. This association between adenocarcinoma and malakoplakia has been previously described [ 2 , 6 ].…”

“…Zhang et al . [ 2 ] described one of the larges published series including 26 patients with gastrointestinal malakoplakia, 88% of the cases affecting colon and rectum. The median age of presentation was 64 years, with a higher rate of women (62%).…”

“…The median age of presentation was 64 years, with a higher rate of women (62%). Diagnosis was an incidental finding in 63% of the cases, generally in the context of colorectal cancer screening [ 2 ]. Interestingly, colorectal cancer was simultaneously diagnosed in 19% of the patients.…”

“…Clinical diagnosis is uncommon. Differential diagnosis of malakoplakia is broad, including conditions like solid neoplasms, inflammatory bowel disease, xanthogranulomatous pyelonephritis, tuberculosis and Whipple disease [ 1 , 2 , 5 , 7 , 8 ]. Radiological findings are also highly unspecific [ 4 , 9 ].…”

“…First described in 1902 by Michaelis and Gutman [ 1 ], it affects more frequently the urinary tract and gastrointestinal system, specially the descending colon, sigmoid and rectum [ 2 ].…”