How do physicians diagnose histoplasmosis?
The symptoms and signs of histoplasmosis are not specific enough to establish the diagnosis. The diagnosis rests upon demonstrating the fungus or an immune response to the fungus. Some of the many diagnostic laboratory tests available include the following:
- Cultures of body fluids or tissues to identify the fungus
- Detection of surface markers of Histoplasma in a urine test
- Blood tests to measure antibody response to Histoplasma
- Microscopic examination of samples of infected tissues
Chest X-rays in people with acute histoplasmosis are usually normal. However, so-called coin lesions or histoplasmomas may be seen in the chest X-ray of people with healed histoplasmosis. These are round accumulations of scar tissue. Calcification of lymph nodes around the bronchi may be evidence of prior healed infections. Depending on the severity and stage of the disease, infiltrates or other changes may be apparent on X-rays.
CT scans are useful to identify areas of spread in disseminated histoplasmosis.