Colonic Infection by Histoplasma capsulatum in a Liver Transplant Patient: A Case Report

Histoplasmosis is an infection caused by the dimorphic fungus Histoplasma capsulatum. While the lungs are the most common site of infection, disseminated disease affecting multiple organs can occur, particularly in immunocompromised patients. Gastrointestinal histoplasmosis is usually diagnosed in the context of disseminated disease and can present in any part of the digestive system, the ileum being the most frequently affected. We report the case of a 60-year-old female patient who underwent liver transplant for alcoholic liver cirrhosis. The patient had a 10 mm polypoid lesion in the sigmoid colon diagnosed in a screening colonoscopy performed 8 months prior to the transplant, but biopsy was not done for fear of bleeding due to extensive anorectal varices. There were no other lesions in the rest of the colon at that time. Four months after the transplant, the patient was asymptomatic and was submitted to a control colonoscopy, which showed 8 polypoid lesions in different parts of the colon, all of which were biopsied. Histologic results showed extensive infiltration of the colonic mucosa by Histoplasma capsulatum. Imaging and laboratorial screening for other sites of infection was negative, and the patient was treated with itraconazole for 12 months. A marked reduction in the dose of tacrolimus was necessary to maintain therapeutic levels during itraconazole treatment. Asymptomatic isolated colonic histoplasmosis is an uncommon manifestation of infection by Histoplasma capsulatum, with no previous reports in the literature of this condition affecting liver transplant recipients. This manuscript is compliant with the Helsinki Congress and the Istanbul Declaration.