Disseminated histoplasmosis

Dr. Flemming presented a fascinating case of a young man with a history of high risk sexual behavior who presented with subacute progressive dyspnea on exertion, found to have sepsis, multiorgan damage with transaminitis, pancytopenia, and diffuse reticulonodular opacities on chest x-ray. An extensive evaluation subsequently resulted in a diagnosis of disseminated histoplasmosis and AIDS.

Histoplasma capsulatum

Histoplasma capsulatum

Disseminated Histoplasmosis (DH): A Primer from HIV Insite:

  • Histoplasma is the most common endemic mycosis in patients with AIDS. in the US, it primarily affects those living the valleys of the Ohio and Mississippi rivers in the US.
  • In patients with AIDS, histoplasmosis presents as a progressive disseminated infection in 95% of cases. The majority of cases present with CD4 counts <150 data-preserve-html-node="true" with a median of 50 cells/uL. Typical presenting complaints include subacute fever, weight loss, and malaise. In roughly half of patients, vague respiratory symptoms are reported.
  • The most common clinical findings include fever, hepatomegaly, splenomegaly, and generalized lymphadenopathy though presentations can be quite variable and include skin, gastrointestinal, neurological, and endocrine presentations as well.
  • Laboratory findings are generally nonspecific with leukopenia, anemia, and thrombocytopenia. A markedly elevated LDH and serum ferritin >10kng/mL is also compatible with DH
  • Chest imaging typically reveals a diffuse interstitial/reticulonodular pattern that can resemble chest imaging of PJP pneumonia or miliary TB. Notably, in one study of patients with AIDS and DH, half had normal chest radiographs. (2)
  • In patients with AIDS, H capsulatum antigen detection in urine is ~95% sensitive. Serum antigen testing is ~85% sensitive.
  • Preferred treatment for DH is amphotericin B at least for an initial course with a subsequent switch to itraconazole to once the patient has shown clinical improvement. The optimal duration of therapy is contingent on immunologic recovery on HAART; if CD4 counts recover >150, ~12 weeks total antifungal therapy appears to be adequate to prevent relapse.

Thanks again to Dr. Fleming for the excellent case, and thanks to Dr. Chiovaro for reminding us of the HIV Insite resource (hivinsite.ucsf.edu), from which most of this information is sourced.

References: 1) “Comprehensive, up-to-Date information on HIV/AIDS treatment and prevention from the University of California San Francisco.” Histoplasmosis and HIV Infection, UCSF, 8 Mar. 2006, hivinsite.ucsf.edu/InSite?page=kb-05-02-06#S1X. 2) Conces DJ, Jr., Stockberger SM, Tarver RD, Wheat LJ. Disseminated histoplasmosis in AIDS: findings on chest radiographs. AJR Am J Roentgenol 1993; 160:15-9.