Gastrointestinal Histoplasmosis Mimicking Intestinal Tuberculosis and Crohn's Disease: Ileocecal Involvement in an...

Gastrointestinal histoplasmosis is an under-recognized manifestation of disseminated Histoplasma capsulatum infection. Its ileocecal predilection closely mimics intestinal tuberculosis (TB) and Crohn's disease, posing serious diagnostic challenges, particularly in TB-endemic regions. A 26-year-old immunocompetent male presented with a 3-month history of diffuse abdominal pain, hematochezia, and 16 kg weight loss. He had received 60 days of empirical four-drug anti-tubercular therapy (ATT) without improvement. Examination revealed cachexia, pallor, digital clubbing, pedal oedema, a hard palate ulcer, and small cervical lymphadenopathy. Investigations showed microcytic anemia, C-reactive protein (CRP) 143.35 mg/L, hypoalbuminemia (2 g/dL), hyponatremia, and fecal calprotectin of 1849.47 μg/g. Magnetic resonance enterography (MRE) suggested multi-segmental small bowel disease consistent with Crohn's disease. Sequential colonoscopies revealed ulcero-nodular lesions involving the distal ileum, ileocecal valve, and caecum. Initial biopsies were inconclusive. Repeat deep tissue biopsy from the caecum and ileocecal valve identified intracellular narrow-based budding yeast forms with eccentric nuclei, consistent with H. capsulatum. GeneXpert and Quantiferon-TB gold plus were negative. Cervical lymph node fine-needle aspiration cytology (FNAC) confirmed disseminated disease. HIV testing was negative. Itraconazole was initiated, followed by liposomal amphotericin B. On day 15, the patient developed catastrophic lower gastrointestinal hemorrhage, resulting in refractory hemodynamic collapse and death. Disseminated histoplasmosis should be considered in the differential diagnosis of ileocecal disease even in immunocompetent patients from TB-endemic regions. Histopathological confirmation through deep tissue biopsy is critical prior to immunosuppressive therapy. Delayed diagnosis carries significant mortality risk.