S1857 Gastrointestinal Histoplasmosis in an Immunocompetent Adult in a Non-Endemic Region

Abstract

Introduction: Histoplasma capsulatum is an endemic fungus and infection is rarely seen in the United States outside of the Ohio and Mississippi River regions. Disseminated infection is typically seen in immunocompromised patients and primary gastrointestinal involvement is rare. We report the case of an immunocompetent adult who was diagnosed with disseminated histoplasmosis with primarily gastrointestinal symptoms. Case description/methods: A 34-year-old male with history of developmental delay and prior seizures presented with seven months of intermittent bloody diarrhea, abdominal pain, fever and chills. He had a similar presentation previously at another hospital and underwent colonoscopy with evidence of multiple ulcers throughout the colon. He was empirically treated with antibiotics but re-presented due to persistent symptoms. Patient was intermittently febrile on admission. Exam showed diffuse abdominal tenderness to palpation. Labs were notable for Hgb 9.1 g/dL and, WBC 12.3 × 10^9 cells/L Stool calprotectin 1570 mcg/g. CT abdomen showed diffuse colonic thickening. Colonoscopy showed discontinuous scattered non-bleeding deep ulcers throughout the entire colon (Figure 1) which were biopsied. Pathology showed histiocytes with intracellular fungal elements. Even duodenal biopsies showed intracellular fungal elements though the duodenal mucosa appeared normal aside from some lymphoid aggregates on upper endoscopy. Urine histoplasma galactomannan antigen was positive. He had no evidence of pulmonary disease. Further history revealed that the patient had never traveled outside of California but did have some close contact with relatives from Minnesota prior to the onset of symptoms. Other infectious work-up including Aspergillus, HIV, CMV, Coccidiomycosis, Cryptococcus were all normal. He was initially treated with oral itraconazole with no improvement of his symptoms, however symptom resolved after initiating IV amphotericin. Genetic testing is pending for underlying immunodeficiency. Discussion: This unique case illustrates disseminated histoplasmosis with mainly gastrointestinal symptoms in a seemingly immunocompetent adult in a non-endemic area. The patient had diffuse small bowel and colonic involvement led to symptoms mimicking inflammatory bowel disease and he even had a markedly elevated calprotectin. Prior case series of disseminated histoplasmosis have reported 100% mortality when untreated. Endoscopic biopsies were crucial to help make the diagnosis and appropriate therapy.Figure 1.: Deep, non-bleeding ulcerations found in transverse colon on colonoscopy.Table 1.: EGD and colonoscopy biopsy results.