Clinical issue of Differential Diagnosis of Imported Mycosis: A Case Report of a Bolivian Man with Disseminated Histoplasmosis which Mimicked Miliary Tuberculosis

A 26-year-old man from Bolivia who presented with a 1-month history of fever was referred to Gunma University Hospital. Initial tests revealed that revealed positive results for infection with human immunodeficiency virus (HIV) and chest computed tomography (CT) showed diffuse pulmonary micronodules suggestive of miliary tuberculosis. Polymerase chain reaction (PCR) and culture tests for tuberculosis yielded negative results. However, the patient was admitted to another hospital due to worsening of the respiratory symptoms, and initiated on anti-tuberculosis treatment. Despite the treatment, however, the patient's condition deteriorated and he was transferred in a state of septic shock to the intensive care unit of Gunma University Hospital. He was initiated on broad-spectrum antibiotic, antifungal, and antiretroviral therapy but failed to show improvement and died a few days later due to multiple organ failure. Postmortem examination revealed disseminated yeast-like fungi in multiple organs, including the lungs, liver, spleen, and bone marrow. Given the patient's background, we considered the possibility of imported mycosis. Using a pan-fungal PCR protocol, the causative pathogen was genetically identified as Histoplasma capsulatum. Based on this result, the patient's condition was diagnosed as disseminated histoplasmosis. This case highlights the importance of considering histoplasmosis in the differential diagnosis of patients who present with features mimicking miliary tuberculosis, particularly in those with a travel history to endemic regions.