S1724 Colonic Histoplasmosis: An Uncommon Presentation of Disseminated Histoplasmosis in an Immunocompetent Patient

Abstract

INTRODUCTION: Histoplasmosis is an invasive mycosis caused by inhaling the spores formed by the environmental mold Histoplasma capsulatum. It occurs commonly in immunodeficient patients however, healthy hosts can be affected if a large number of conidia is inhaled. Here we present an intricate case of disseminated histoplasmosis in an immunocompetent patient. CASE DESCRIPTION/METHODS: An 83-year-old man with a history of coronary artery disease, atrial fibrillation, diabetes complicated by gastroparesis, and COPD who presented with a 6-month history of unintentional weight loss, normocytic anemia, abdominal crampings, and chronic non-bloody diarrhea. Previous studies included an upper endoscopy 9 years prior, showing hiatal hernia but otherwise normal with a negative H pylori test at that time. Colonoscopy 7 years prior evidencing internal hemorrhoids, diverticulosis, and one tubular adenoma in the ascending colon.He underwent extensive workup upon admission, including negative stool culture, ova and parasites, HIV screen, Giardia ELISA, and C. difficile PCR; normal C reactive protein, stool lactoferrin, TSH and celiac panel. Colonoscopy showed one 9 mm polyp in the ascending colon (Figure A), 1 polyp in the transverse colon, diverticulosis coli, and internal hemorrhoids. Biopsy of the ascending polyp revealed fragments of tubular adenoma and focally eroded colonic mucosa with mixed histiocytes-rich mucosal inflammation including intracellular organisms, favoring Histoplasma capsulatum (Figures B and C). Computed tomography (CT) abdomen showed 1.7 cm left adrenal nodule, concerning for disseminated infection. CT neck was performed for evaluation of jaw pain and swelling that showed parotitis and multiple brain lesions, confirmed by MRI. The diagnosis of disseminated histoplasmosis was confirmed with a positive urinary Histoplasma antigen. The patient was started on liposomal amphotericin B but given advanced age, multiple comorbidities, and progressive disease at the time of diagnosis, the patient opted for comfort care measures. DISCUSSION: Histoplasmosis is the most common endemic fungal disease in both healthy and immunocompromised patients with more than several thousand infections reported yearly. GI histoplasmosis is unusual in immunocompetent hosts accounting for 0.05% of cases however in 50% to 70% of cases, it occurs in disseminated form. We believe that early diagnosis and proper management prevents the progression of the disease and potentially death.Figure 1Figure 2Figure 3