Disseminated Histoplasmosis Due to Anti-IFN-γ Autoantibodies-Associated Immunodeficiency.

Background: Disseminated histoplasmosis caused by the temperature-dependent dimorphic fungus Histoplasma capsulatum is an invasive fungal disease rarely reported in southern China. Here, we report a case of disseminated histoplasmosis due to anti-IFN-γ autoantibodies (AIGA)- associated immunodeficiency.

Case presentation: We present the case of a 57-year-old HIV-negative female patient with disseminated histoplasmosis in southern China. The patient showed progressively enlarging multiple clavicular, neck, and upper chest skin nodules and dyspnea, which led to the initial suspicion of pulmonary tuberculosis or lung cancer. Bacterial cultures results were negative. Histopathology of a skin tissue showed infectious granulomas. Disseminated histoplasmosis was diagnosed via next-generation sequencing (mNGS) and fungal culture. Furthermore, enzyme-linked immunosorbent assay results from a peripheral blood confirmed that the patient had a high-titer of AIGA.

Conclusion: This case prompts clinicians to consider histoplasmosis an important differential diagnosis in a region where talaromycosis is highly endemic. This case report emphasizes that clinicians should be vigilant for immunodeficiency and consider testing for AIGA in HIV-negative patients who are suspected of having complex opportunistic infections.