North American blastomycosis in an immunocompromised patient.

Blastomycosis is a subacute or chronic deep mycosis caused by a dimorphic fungus, Blastomyces dermatitidis, that generally produces a pulmonary form of the disease and, to a lesser extent, extrapulmonary forms, such as cutaneous, osteoarticular, and genitourinary. Both immunocompetent and immunocompromised individuals can be infected, but more severe disease occurs in the immunocompromised. Blastomycosis can be diagnosed by culture, direct visualization of the yeast in affected tissue, antigen testing, or a combination of these methods.