Case Report
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Endosc. Oct 16, 2022; 14(10): 648-656
Published online Oct 16, 2022. doi: 10.4253/wjge.v14.i10.648
Gastrointestinal histoplasmosis complicating pediatric Crohn disease: A case report and review of literature
C Quinn Miller, Omer A M Saeed, Katrina Collins
C Quinn Miller, Omer A M Saeed, Katrina Collins, Department of Pathology, Indiana University School of Medicine, Indianapolis, IN 46202, United States
Author contributions: Miller CQ served as the primary author; Miller CQ and Collins K are responsible for this literature review; Miller CQ, Saeed OAM, and Collins K were responsible in the construction of the manuscript; Collins K served as the senior author, provided invaluable educational input and managed the edits of the manuscript, and guided the primary author through the submission process; All authors read, revised, and gave approval of the manuscript.
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Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
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Corresponding author: Katrina Collins, MD, Assistant Professor, Department of Pathology, Indiana University School of Medicine, 350 W 11th Street, Indianapolis, IN 46202, United States.
Received: July 17, 2022
Peer-review started: July 17, 2022
First decision: September 5, 2022
Revised: September 5, 2022
Accepted: September 21, 2022
Article in press: September 21, 2022
Published online: October 16, 2022

Infection with Histoplasma capsulatum (H. capsulatum) can lead to disseminated disease involving the gastrointestinal tract presenting as diffuse abdominal pain and diarrhea which may mimic inflammatory bowel disease (IBD).


We report a case of 12-year-old boy with presumptive diagnosis of Crohn disease (CD) that presented with several months of abdominal pain, weight loss and bloody diarrhea. Colonoscopy showed patchy moderate inflammation characterized by erythema and numerous pseudopolyps involving the terminal ileum, cecum, and ascending colon. Histologic sections from the colon biopsy revealed diffuse cellular infiltrate within the lamina propria with scattered histiocytic aggregates, and occasional non-necrotizing granulomas. Grocott-Gomori’s Methenamine Silver staining confirmed the presence of numerous yeast forms suggestive of Histoplasma spp., further confirmed with positive urine Histoplasma antigen (6.58 ng/mL, range 0.2-20 ng/mL) and serum immunoglobulin G antibodies to Histoplasma (35.9 EU, range 10.0-80.0 EU). Intravenous amphotericin was administered then transitioned to oral itraconazole. Follow-up computed tomography imaging showed a left lower lung nodule and mesenteric lymphadenopathy consistent with disseminated histoplasmosis infection.


Gastrointestinal involvement with H. capsulatum with no accompanying respiratory symptoms is exceedingly rare and recognition is often delayed due to the overlapping clinical manifestations of IBD. This case illustrates the importance of excluding infectious etiologies in patients with “biopsy-proven” CD prior to initiating immunosuppressive therapies. Communication between clinicians and pathologists is crucial as blood cultures and antigen testing are key studies that should be performed in all suspected cases of histoplasmosis to avoid misdiagnosis and inappropriate treatment.

Keywords: Crohn disease, Disseminated histoplasmosis, Endoscopy, Colon, Inflammatory bowel disease, Immunosuppression, Case report

Core Tip: Impaired cell-mediated immunity is known to increase the risk for disseminated histoplasmosis and has been described in the setting of Crohn disease (CD) treated with immunosuppressant agents. Endoscopically, the appearance of histoplasmosis varies and includes features of inflammatory mucosal changes. Increasing awareness of this condition is critical to avoid misdiagnosis and inappropriate treatment, particularly in the setting of underlying CD. While no specific recommendations are available, immunosuppressive therapy may be safely initiated in some cases when there appears to be effective response to antifungal therapy and the patient can be monitored closely.