S1813 Gut Feeling: Isolated Colonic Histoplasmosis

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INTRODUCTION: Histoplasmosis primarily manifests in humans as asymptomatic pulmonary infections and gastrointestinal and hepatic involvement is frequent in disseminated disease. However, isolated involvement is rare and underreported. We present a case of a 65-year-old male with history of hepatitis C that was found to have asymptomatic isolated histoplasmosis on screening colonoscopy and treated with a 6-month course of fluconazole. CASE DESCRIPTION/METHODS: A 65-year-old male with a history of hypertension, GERD, and hepatitis C with completed interferon-Ribavarin treatment was referred from his primary care physician to gastroenterologist for screening colonoscopy. The patient denied any symptoms and previous colonoscopy was unremarkable. EGD was done for previous Barret’s esophagus and showed mild distal esophagitis and gastritis. Colonoscopy showed an ulcerated 3 cm mass in the cecum, multiple colon polyps in ascending colon, rectal ulcer in a polyp, and three sessile polyps of benign appearance ranging from 5 mm to 1 cm. Biopsies were taken of the cecal mass and piece-meal polypectomy was done for rectal ulcer. The ascending colon polyps were not removed as the patient would possibly need right hemicolectomy for the large cecal lesion. Pathology of the antral biopsy showed mild reactive gastropathy with no H. Pylori or intestinal metaplasia. Colon cecum, transverse, and rectal biopsies showed mucosa containing innumerable histiocytic CD68 positive/GMS positive fungal organisms consistent with Histoplasma capsulatum. The patient was referred to infectious disease and started on fluconazole 200 mg BID for 6 months and completed treatment. DISCUSSION: Isolated gastrointestinal histoplasmosis is rare and disseminated disease can present with moderate to severe infections that can be life-threatening. As seen in our patient, it can occurs in immunocompromised patients such as those on immunosuppressant medications including long-term steroids or conditions such as malignancies or chronic infections like HIV or HCV. The role of treatment in isolated histoplasmosis is uncertain, and itraconazole is typically preferred unless there is concomitant use of proton pump inhibitors or H2 blockers that will limit its absorption. Clinicians should be mindful of occult infections in immunocompromised patients and utilizing appropriate evaluation and treatment for these conditions.Figure 1.: Ulcerated mass 3 cm in cecum on colonoscopy.Figure 2.: Rectal ulcer in polyp.Figure 3.: Biopsy of colonic mucosa showing CD 68 positive and GMS positive unnumerable fungal organisms consistent with Histoplasma capsulatum.