Blastomycosis in a patient with psoriasis: treatment with ketoconazole.

Slowly enlarging verrucous skin lesions occurred in a 42-year-old man with psoriasis after he received systemic steroid treatment. Examination of skin biopsy specimens established the diagnosis of blastomycosis. Extensive evaluation revealed no other organ system involvement. The lesions of blastomycosis responded well to ketoconazole therapy; the psoriasis was unaffected. This report reviews the natural history of blastomycosis, speculates on the patient's immune status at the time of infection, and comments on the use of ketoconazole in the treatment of blastomycosis and psoriasis.