Gastrointestinal Histoplasmosis: Unveiling the Colon Cancer Facade in Crohn's Disease

Abstract Background: The therapeutic landscape for inflammatory bowel diseases (IBD) has expanded with the advent of tumor necrosis factor-α (TNF) inhibitors, yet hurdles persist despite these strides. One such challenge arises from the increased vulnerability to opportunistic infections, notably histoplasmosis. Although histoplasmosis typically resolves on its own in individuals with healthy immune systems, its unconventional gastrointestinal manifestations in IBD patients can pose a diagnostic conundrum. Case presentation: Here, we delve into the narrative of a 72-year-old woman diagnosed with Crohn's disease on infliximab monotherapy presented with escalating lower abdominal discomfort, nausea, vomiting, bloody diarrhea, and unintended weight loss over the preceding four weeks. Magnetic resonance enterography (MRE) highlighted a 5 cm thickened wall and restricted diffusion in the transverse colon, raising suspicions of malignancy. Colonoscopy revealed a sizable 15 mm deep and cratered transverse colon ulcer, prompting concern for colon cancer. However, a biopsy from the ulcer only revealed acute nonspecific inflammation. Given the patient's deteriorating condition and persistent neoplasm suspicion, she underwent total abdominal colectomy with ileorectal anastomosis. Surgical pathology confirmed multifocal transmural fungal colitis, consistent with histoplasmosis. Conclusion: Clinicians should have a high index of suspicion for fungal colitis in patients previously in remission on immunosuppressive therapy and caution against dismissing histoplasmosis solely based on negative biopsy results. Repeated biopsy may be warranted to ensure comprehensive evaluation and accurate diagnosis.