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Published on: November 5, 2019
Gastrointestinal Malakoplakia: Clinicopathologic Analysis of 26 Cases
Yang Zhang1, Kathleen Byrnes2, Dora Lam-Himlin3
1Department of Pathology, Johns Hopkins School of Medicine, Baltimore, MD.
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.
Insights
Gastrointestinal malakoplakia, an inflammatory condition, is typically an incidental finding. Despite potential confusion with lymphoma, it is a benign condition with no recurrence observed in patients.
Area of Science:
- Gastroenterology
- Pathology
- Oncology
Background:
- Malakoplakia is an inflammatory condition resulting from defective macrophage response to bacterial infection.
- Gastrointestinal malakoplakia presents unique clinicopathologic features requiring characterization.
Purpose of the Study:
- To detail the clinicopathologic manifestations of gastrointestinal malakoplakia.
- To identify potential diagnostic challenges and their resolutions.
Main Methods:
- Retrospective review of 26 gastrointestinal malakoplakia cases from six institutions.
- Analysis of hematoxylin and eosin-stained slides and ancillary stains.
- Review of clinicopathologic features and patient follow-up.
Main Results:
- The study included 26 cases, predominantly affecting women (62%) with a mean age of 64.
- Colorectal involvement was most common (n=23), with histiocytes containing Michaelis-Gutmann bodies observed in all cases.
- Associated findings included adenocarcinoma (n=5) and lymphoid aggregates that mimicked lymphoma in some colon biopsies.
Conclusions:
- Gastrointestinal malakoplakia is a benign, incidental finding.
- While histologically similar to other sites, prominent lymphoid responses in colon biopsies and rare Tropheryma whipplei antibody positivity can cause diagnostic confusion.
- Prompt identification and differentiation from malignancy are crucial to avoid unnecessary interventions.
