Miliary Histoplasmosis in a Patient with Rheumatoid Arthritis

Miliary histoplasmosis is a rare presentation that may mimic miliary tuberculosis. We report a case of miliary histoplasmosis in a 52-year-old male who was being treated with hydroxychloroquine, methotrexate, and sulfasalazine for his rheumatoid arthritis and presented to the emergency department with shortness of breath and fevers. Computed tomography (CT) chest revealed miliary pulmonary nodules. Urine Histoplasma antigen and serum Histoplasma antigen were negative; however, Coccidioides immitis complement immunofixation assay and Coccidioides IgM were positive. The patient was initiated on treatment for pulmonary coccidioidomycosis and immunosuppression was held. However, a few days later, Histoplasma capsulatum was isolated from cultures from bronchoscopy. This case highlights the difficulty in diagnosing histoplasmosis in immunocompromised patients and the importance of having a broad differential diagnosis for miliary pulmonary nodules. Tissue culture and histopathology remain the gold standard for the diagnosis of histoplasmosis. Further research needs to be conducted to determine the optimal duration of histoplasmosis treatment in immunocompromised patients.