Describe the epidemiology and pathogenesis of blastomycosis. Illustrate common and uncommon imaging features of blastomycosis along with the entities that it mimics. Describe key elements that should raise concern for blastomycosis.

Blastomycosis is an endemic fungal infection caused by the thermally dimorphic fungi Blastomyces dermatitidis and Blastomyces gilchristii (Figure 1). It occurs primarily in North America, especially in the upper Midwestern United States and around the great lakes in Canada (Figure 2). Cases of blastomycosis occurring outside of North America have been reported, nearly all exported from endemic areas with very few reports (about 100) of indigenous cases in Africa and India. The fungus grows primarily in moist soil near water, and disruption of the soil...

1. Acute pulmonary blastomycosis mimicking community-acquired pneumonia (Figure 3) Pulmonary infection is reported in >79% of patients with documented blastomycosis. Symptoms develop between 3 weeks to 3 months after inhalation of spores and are similar to community-acquired pneumonia. Patients most commonly present in autumn and winter because of the latency between exposure and clinical disease. The most common radiographic finding is consolidation, typical of many other lower respiratory tract infections. Air bronchograms are present in up to 88% of cases. Small satellite nodules in the...

Blastomycosis is an endemic fungal infection primarily occurring in North America but can be encountered elsewhere because of increase in travel and immigration. The diagnosis is often delayed because other infections or malignancy can have similar imaging and clinic manifestations, leading to delay in appropriate treatment. Familiarity with risk factors, imaging findings, and certain clinical and imaging clues can help the radiologist suggest blastomycosis as the possible cause of a patient’s illness. These include: 1. Demographics · Lived or travelled to endemic areas. · Occupation...

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Maria Daniela Martin, M.D. Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA. Jeffrey P. Kanne, M.D. Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA. Cristopher Meyer, M.D. Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.