Rapid diagnosis of blastomycosis

A previously healthy man is hospitalized for a two-month illness characterized by productive cough, dyspnea, and weight loss. Empiric antibiotic therapy for community-acquired pneumonia failed to affect the symptoms. Six weeks later, the patient was hospitalized again, now with respiratory distress. Chest radiogram showed diffuse patchy nodular infiltrates. Antibiotics were modified but the patient did not improve and required assisted ventilation the following day. Nodular skin lesions were noted on his legs. Which two tests are most likely to assist you in making a prompt diagnosis? a. Biopsy of skin lesion for cytology and fungal stain. Correct. b. Bronchoscopy with BAL for cytology, fungal stain, and fungal antigen. Correct. c. Culture of skin biopsy and BAL. Incorrect. Comment. Blastomycosis was diagnosed by demonstration of budding yeast in the sputum and skin biopsy. Despite initiation of amphotericin B the following day, the patient died of respiratory failure and shock. A prolonged illness at presentation suggested fungal disease, and occurrence in Indiana suggests the potential of histoplasmosis or blastomycosis, but productive cough is more consistent with blastomycosis. Clinicians often fail to consider the diagnosis of blastomycosis perhaps in part because of unfamiliarity with its characteristic clinical findings. Blastomycosis was initially suspected in less than 20% of cases in one report, pneumonia being the more common working diagnosis, followed by cancer or tuberculosis [1]. In a recent report of four fatal cases, failure to consider the diagnosis contributed to poor outcome [2]. In three of the four patients, symptoms were present for 4-12 weeks prior to diagnosis and blastomycosis was not considered during earlier hospitalizations. The authors emphasized the need for education about blastomycosis, with a focus on symptom recognition, approach to diagnosis, and appropriate therapy. Misdiagnosis as community-acquired pneumonia and failure to consider blastomycosis in the differential diagnosis is all too common in fatal cases. Several tests may be used for rapid diagnosis of blastomycosis, see Table 1. In patients with sputum production, diagnosis may be made by cytologic analysis of sputum specimens [3]. Cytology was the first method for diagnosis in 57.7% of cases, KOH wet mount in 28.2%, and histology in 11.5% [3]. The overall sensitivity was 93.2% for cytology, 85.1% for histology, 66.4% for culture, and 48.4% for KOH preparation. Bronchoscopy to obtain bronchoalveolar lavage specimens or washings may be helpful in patients who do not produce sputum, with a sensitivity of nearly 75% [4,5]. Bronchoscopy specimens should be …