Lower gastrointestinal bleeding (LGIB) is very common in the hospital setting. Most bleedings stop spontaneously, but rare infectious causes of LGIB may lead to rapid and serious complications if left untreated and are sometimes very difficult to diagnose preoperatively.
We described a young man with poorly controlled Type I diabetes mellitus and chronic alcohol abuse who presented with acute altered mental status. During his hospitalization for treatment of diabetic ketoacidosis, acute renal failure, and sepsis, he suddenly developed massive hematochezia of 1500 mL. Colonoscopy was performed and a deep ulcer covered with mucus with peripheral elevation was noted at the transverse colon. Biopsy of the ulcer later revealed nonpigmented, wide (5-20 µm in diameter), thin-walled, ribbon-like hyphae with few septations and right-angle branching suggestive of mucormycosis demonstrated by Periodic acid-Schiff stain. He received 2 months of antifungal treatment. Follow up colonoscopy post-treatment was normal with no ulcer visualized.
Early diagnosis and treatment of gastrointestinal (GI) mucormycosis infection is critical but can be challenging, especially in the setting of massive hematochezia. Therefore, clinical awareness for immunocompromised patients and prompt antifungal prophylaxis in cases with high suspicion of infection are essential.

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