Gastrointestinal Basidiobolomycosis: A Rare Fungal Disease Mimicking Colon Cancer

Gastrointestinal basidiobolomycosis (GIB) is an uncommon fungal infection caused by <i>Basidiobolus ranarum</i>, an environmental saprophyte found in soil, decaying vegetation, and the gastrointestinal tracts of reptiles and amphibians. It primarily affects immunocompetent individuals and can closely mimic colonic malignancy or inflammatory bowel disease, often leading to diagnostic delays. We describe the case of a 52-year-old immunocompetent South Asian male who presented with right lower quadrant pain, diarrhea, and coffee-ground vomiting. Colonoscopy with superficial biopsies suggested eosinophilic colitis, while CT raised suspicion for right-sided colonic carcinoma. Due to progressive symptoms and risk of obstruction, surgical resection was performed. Histopathology revealed broad, pauciseptate fungal hyphae surrounded by the Splendore-Hoeppli phenomenon, confirming GIB. The patient is currently undergoing a six-month course of oral itraconazole and, at the six-week follow-up, showed marked improvement, including weight gain and resolution of symptoms. GIB should be considered in patients from endemic areas who present with abdominal masses, eosinophilia, and a poor response to immunosuppressive therapy. Early diagnosis through deep tissue sampling enables timely initiation of antifungal treatment and may help prevent unnecessary surgical intervention.