Disseminated Histoplasmosis Presenting as an Obstructive Mass in Crohn's Disease: A Case Report.

Abstract

Introduction: Patients with Crohn's disease are at increased risk for both colorectal carcinoma and opportunistic infections due to chronic inflammation and long-term immunosuppressive therapy. Fungal infections such as histoplasmosis may mimic malignancy or inflammatory exacerbation, leading to diagnostic delay.

Case presentation: We report a 50-year-old woman with a 10-year history of Crohn's disease treated with a tumor necrosis factor inhibitor and an interleukin-23 antagonist who presented with abdominal pain, diarrhea, and colonic masses. Colonoscopic biopsies showed dense inflammation with necrotizing granulomata. Grocott's methenamine silver stain and immunohistochemistry revealed intracytoplasmic budding yeasts consistent with Histoplasma capsulatum, confirmed by polymerase chain reaction. The urinary Histoplasma galactomannan antigen test was negative, while serum 1,3 β-D-glucan was positive. The patient was successfully treated with amphotericin B followed by itraconazole, with complete clinical recovery. Retrospective history revealed travel to Ecuador.

Conclusion: Gastrointestinal histoplasmosis can closely mimic Crohn's flare or malignancy, especially in immunosuppressed patients. Careful histopathologic evaluation and integration of clinical and laboratory findings are essential for timely diagnosis and effective antifungal therapy.