North American blastomycosis.

Pulmonary blastomycosis may present as a mass that resembles a lung tumor on radiographs. Blastomycosis should be suspected if the patient has an associated skin lesion and known risk factors, such as living in or visiting endemic areas or participating in activities that involve frequent contact with soil. If these risk factors are kept in mind, the diagnosis of blastomycosis may be established before a thoracotomy is performed unnecessarily.