S3794 Unexpected Cause of Acute Gastrointestinal Bleeding: Disseminated Histoplasmosis of the Gastrointestinal Tract

Introduction: Histoplasmosis in AIDS patients is a serious opportunistic infection and can affect nearly any organ system. However, it is a rare occurrence when this disease manifests as acute gastrointestinal (GI) bleeding. We present a case of a 40-year-old man with a history of AIDS who presented with non-specific symptoms of weight loss, hematochezia and melena. Case Description/Methods: A 40-year-old man with a history of IV drug use and AIDS presented with several weeks of rectal pain, hematochezia, melena, fatigue, and weight loss. He appeared cachectic with cervical lymphadenopathy and was hypotensive and tachycardic on arrival. Labs showed HGB 6.7 g/dL. Computed tomography abdomen/pelvis revealed circumferential rectal wall thickening suggestive of proctitis. Due to ongoing anemia an upper endoscopy performed was unremarkable, while flexible sigmoidoscopy revealed a rectal fistula and ulcerated mucosa, though active bleeding limited visualization. Colonoscopy attempts were unsuccessful, and a tagged RBC scan showed no active bleeding. Cervical lymph node biopsy demonstrated small intracytoplasmic yeast forms with Grocott methenamine silver (GMS) stain positive for fungal organisms. Rectal biopsy confirmed fungal organisms. Positive histoplasma antigen confirmed disseminated histoplasmosis with GI involvement. The patient was treated with 14 days of liposomal amphotericin B, followed by itraconazole and antiretroviral therapy, with resolution of bleeding and stabilization of hemoglobin. Discussion: Histoplasmosis with GI involvement occurs about 70-90% of time in patients with AIDS. It has nonspecific symptoms consisting of diarrhea, fever, abdominal discomfort, and weight loss which can resemble the symptoms of multiple GI conditions. However, acute GI bleeding is a rare initial manifestation. Histoplasmosis of the GI tract may appear as nodules, mass-like lesions, and ulcerations that can cause severe bleeding. In AIDS patients, lymphomas have a high incidence and can also present with nonspecific symptoms, making the diagnosis of histoplasma difficult to diagnose without clinical suspicion. The diagnosis is done with endoscopic evaluation and biopsies identifying yeast forms. Furthermore, blood and urine antigen tests aid in the diagnosis. Outcomes are favorable with timely treatment using liposomal amphotericin followed by itraconazole for 12 months. This case highlights the unusual presentation and it can help clinicians broaden their differentials when evaluating GI bleeding in HIV patients.