S4771 A Rare Case of Life-Threatening Bleeding Related to Gastrointestinal Histoplasmosis in a Heart Transplant Recipient

Introduction: Isolated small bowel involvement in gastrointestinal (GI) histoplasmosis presenting as overt bleeding is an exceedingly uncommon condition, even among immunosuppressed individuals, making its diagnosis and management challenging. Case Description/Methods: A 61-year-old man with a history of non-ischemic cardiomyopathy status post heart transplant 4 years ago on tacrolimus and sirolimus, chronic kidney disease stage IV, prior cytomegalovirus viremia, presented with symptoms of fatigue, melena, nausea, and early satiety ongoing for 2 days. On admission, he was afebrile and had mild hypotension and tachycardia. Initial labs revealed a hemoglobin (Hb) 6.1 g/dl, a normal white blood cell and platelet count, and serum creatinine 3.77 mg/dL (baseline 3.5). He received 7 units of packed red blood cells due to blood loss. An esophagogastroduodenoscopy was performed, which revealed abnormal mucosal depositions with central vascular ectasia throughout the duodenum and the jejunum. Active bleeding was noted in 1 of the larger jejunal lesions and was controlled by argon plasma coagulation and PuraStat application. Biopsies were obtained. Despite this, melena and drop in Hb recurred, needing further transfusions. Scintigraphy scan confirmed active jejunal bleeding, which was then treated by interventional radiology guided embolization. Duodenal biopsies revealed histoplasmosis, and the patient was started on itraconazole. Tacrolimus was held temporarily based on trough levels that were affected by drug-drug interactions with itraconazole. The patient did not have any further bleeding or blood transfusions. Due to itraconazole intolerance, intravenous amphotericin B was given for 5 days, then switched to voriconazole. The patient continued to improve with his symptoms through the remaining hospital course. Discussion: GI bleeding occurs in fewer than one-third of cases of histoplasmosis and involves the duodenum in less than 4% of patients without AIDS. Presentations can vary from ulcerations, mucosal inflammation, or strictures, but mucosal depositions with vascular ectasias have not been reported in heart transplant recipients. Anti-fungal therapy was key in treating the infection and associated bleeding. This case underscores the importance of lesional biopsies in transplant recipients with unexplained GI bleeding and highlights the need for careful immunosuppressive management during treatment.