Lower gastrointestinal bleeding (haematochezia) as the initial clue to disseminated histoplasmosis with central nervous system involvement in a renal transplant recipient

Most histoplasmosis infections are asymptomatic or present as a self-limiting pulmonary illness; however, disseminated disease can occur in immunocompromised patients. Lower gastrointestinal (GI) bleeding (haematochezia) without other GI-related symptoms is an uncommon manifestation of disseminated histoplasmosis, posing a diagnostic challenge. We describe a renal transplant recipient in his 70s on chronic immunosuppressive therapy (tacrolimus and mycophenolate mofetil) who initially presented with progressive bilateral lower-extremity weakness and later developed haematochezia during hospitalisation. A colonoscopy was performed for worsening anaemia and haematochezia and revealed a localised ulcerated lesion. Histopathology demonstrated necrotising granulomatous inflammation with intracellular yeast forms on H&E staining, with Grocott methenamine silver stain highlighting oval budding yeast consistent with Histoplasma capsulatum . Serum Histoplasma antigen was positive (5.2 ng/mL). MRI demonstrated multifocal enhancing lesions involving the brain and spinal cord. Cerebrospinal fluid analysis revealed lymphocytic pleocytosis (27 cells/µL, 90% lymphocytes), elevated protein (88.2 mg/dL) and low glucose (48 mg/dL; serum 101 mg/dL), concerning for fungal meningitis in the setting of disseminated histoplasmosis. He was treated with liposomal amphotericin B followed by itraconazole, with a reduction in his tacrolimus dosing from 3 mg in the morning and 2 mg in the evening to 1 mg two times per day to reduce drug-drug interactions and risk of nephrotoxicity. At his 6-week follow-up, his neurologic deficits had significantly improved, and he was ambulating independently.