American Board of Internal Medicine (ABIM) Certification Practice Exam

What percentage of patients with acute progressive disseminated histoplasmosis demonstrate histoplasma antigen in body fluids?

1. 50%

2. 70%

3. 90%

4. 100%

The correct answer is: 90%

In cases of acute progressive disseminated histoplasmosis, around 90% of patients are found to have histoplasma antigen detectable in their body fluids. This statistic is significant because it highlights the high sensitivity of antigen detection in diagnosing this severe form of histoplasmosis, which helps in identifying the infection early and initiating appropriate treatment. Histoplasmosis is an fungal infection caused by Histoplasma capsulatum, and patients with the disseminated form often present with severe systemic symptoms. The presence of antigen in body fluids, such as urine or serum, serves as a crucial biomarker. This is particularly important in cases where culture may be difficult or take time, and the clinical picture can rapidly deteriorate. The other statistics regarding the antigen detection percentages would be lower and do not represent the robust immunologic response typically observed in advanced cases of progressive disseminated histoplasmosis. Therefore, the identification of antigen in about 90% of cases underscores both the diagnostic utility of antigen testing and the severe nature of the condition in such patients.