Chronic Pulmonary Blastomycosis Mimicking Pulmonary Tuberculosis

Blastomyces dermatitidis is a dimorphic fungus endemic to the Mississippi River valley. We describe a rare case of chronic pulmonary blastomycosis complicated by large pulmonary cavitation in a young service member who was misdiagnosed with active pulmonary tuberculosis.

A 25-year-old active duty male presented to his primary care provider with complaints of hemoptysis, fatigue, weight loss, and fever. Computed tomography chest with contrast identified a large cavitary lesion in the right upper lobe (RUL). The patient was admitted to an outside hospital and he underwent bronchoscopy with transbronchial biopsies and bronchoalveolar lavage of the RUL. Histology and cultures were unremarkable however; Histoplasma serum antigen was positive. The patient was empirically treated for active pulmonary tuberculosis and soon discharged. He returned for medical evaluation 3 mo later with continued hemoptysis. Repeat bronchoscopy with transbronchial biopsies of the RUL cavity grew Blastomyces dermatitidis. The patient's symptoms resolved and chest imaging significantly improved with initiation of itraconazole.

Chronic pulmonary blastomycosis can present with a constellation of symptoms that may be indistinguishable from chronic pulmonary histoplasmosis, pulmonary tuberculosis, or lung cancer. Knowledge of endemic diseases and a thorough travel history should be an integral part of a military physician's infectious disease evaluation.