Chiefs Blog

Histoplasma – A Fungus Among Us

Clinicopathologic Conference , referred to as CPC, is a long-standing tradition here at Washington University in St. Louis. The origin of this tradition at WashU can be traced back to the beginning of the 20th century. CPC began at Harvard and then was subsequently adopted at Johns Hopkins. Dr. George Dock, a protégé of Dr. William Osler himself, was a Professor of Medicine at WashU and brought CPC here with him. CPC is a clinical problem solving exercise which remains a favorite among housestaff. Pictured here is “The Pit” in the 1950s, the venue at which CPC was held (Becker Archives). We are very excited to continue the tradition in a new “Virtual Pit.”

Last week – I presented a case of a gentleman with a past medical history of antisynthetase syndrome presenting as a transfer for worsening encephalopathy. The discussant was Dr. Escota. Dr. Escota utilized problem representation to frame the case as: ~70 year old immunocompromised man presents with subacute encephalopathy. In addition – he noted the patient’s symptoms appeared to be a disseminated process and with the patient’s home being in Illinois, the endemic mycosis of histoplasmosis was at the top of his differential. Interestingly, CSF had a neutrophilic pleocytosis. It wasn’t until hospital day 6 that the patient’s urine histoplasma Ag resulted positive. The patient’s blood culture and CSF culture subsequently grew Histoplasma capsulatum.

CNS Histoplasmosis occurs in 5-10% of individuals with disseminated infections and positive CSF cultures only occur in about 25% of patients with CNS involvement. Therefore, antigen or antibody detection remains the most sensitive means to establish the diagnosis. Ultimately, we must rely on our clinical suspicion of disseminated mycoses and patient risk factors to identify these cases early.


Wheat J, Myint T, Guo Y, et al. Central nervous system histoplasmosis: Multicenter retrospective study on clinical features, diagnostic approach and outcome of treatment [published correction appears in Medicine (Baltimore). 2018 Apr;97(16):e0537]. Medicine (Baltimore). 2018;97(13):e0245. doi:10.1097/MD.0000000000010245