Talaromyces marneffei laboratory cross reactivity with Histoplasma and Blastomyces urinary antigen

Talaromyces marneffei is a fungal opportunistic infection usually seen in immunocompromised patients from eastern countries. In the US when examining HIV-patients for suspected fungal infections, laboratory serological tests guide therapy until cultures are available. We present the case of a 35-year-old HIV patient originally from Thailand in which urine lab results were positive for Blastomyces and Histoplasma antigen, but biopsy showed T. marneffei. Concomitantly the patient presented with hyponatremia which was deemed to be from SIADH. We present the first case of a patient with T. marneffei cross reactivity with Blastomyces, Histoplasma and SIADH due to pulmonary disease.