S6135 Disseminated Histoplasmosis Presenting With Duodenal Outlet Obstruction and Pancreatitis in an Immunocompetent Host

Introduction: Histoplasmosis is a systemic fungal infection caused by Histoplasma capsulatum, acquired via spore inhalation in endemic regions. While pulmonary disease is the most common presentation, disseminated histoplasmosis can involve multiple organ systems and is usually seen in immunocompromised individuals. Gastrointestinal (GI) involvement is rare, often underrecognized, and usually presents with vague symptoms such as abdominal pain or diarrhea. Severe complications like ulceration, obstruction, bleeding, or pancreatitis are exceedingly uncommon. Case Description/Methods: We report a rare case of disseminated histoplasmosis in a 76-year-old immunocompetent man with type 2 diabetes, BPH, and gastroesophageal reflux disease who presented with 2 months of progressive nausea, vomiting, 50 lb weight loss, and coffee ground emesis. Computed tomography abdomen showed fat stranding around the pancreatic head and duodenum, consistent with acute pancreatitis. Upper endoscopy revealed an ulcerated, infiltrative-appearing mass with a stricture at the junction of the first and second portions of the duodenum, raising concern for malignancy and duodenal outlet obstruction. Biopsies demonstrated severe active duodenitis with ulceration and budding yeast forms within histiocytes. He was transferred to our facility due to worsening respiratory failure, and recurrent vomiting. Computed tomography imaging showed innumerable pulmonary nodules and mediastinal lymphadenopathy. Urine histoplasma antigen (titer 1:128) and serum antibody testing were positive, and fungal stains confirmed H. capsulatum. He improved initially with itraconazole, but was readmitted for nausea and vomiting with eventual hematemesis 8 weeks later. Repeat esophagogastroduodenoscopy now revealed a Mallory-Weiss tear, LA Grade D esophagitis, a large duodenal ulcer, and a non-traversable ulcerated stricture in D1. Magnetic resonance imaging indicated duodenal wall thickening and groove pancreatitis. Due to recalcitrant symptoms, he underwent exploratory laparotomy and Roux-en-Y gastric bypass; biopsies were benign. His post-operative course was complicated by pulmonary embolism requiring anticoagulation, chronic nausea with poor weight gain, and failure to thrive. Discussion: This case highlights an uncommon, disseminated presentation of histoplasmosis involving the GI tract. Clinicians should maintain a high index of suspicion for fungal infections in patients with unexplained GI pathology, especially those from endemic areas.