Case Presentation: A previously healthy 58 year old male presented with increasing dyspnea for three days. On admission, his heart rate was 110, respiratory rate was 19, and his oxygen saturation was 85% on room air. Chest x-ray revealed bilateral coarse interstitial infiltrates. The patient was started on Vancomycin, Levofloxacin, and Piperacillin-Tazobactam. During the hospital stay, the patient became increasingly hypoxic, with rapid respiratory deterioration. Empiric intravenous steroids were initiated with no clinical improvement. A computed tomography of the thorax was obtained, which revealed bilateral patchy lung consolidation. Bronchoscopy was non-revealing, and the studies from bronchoalveolar lavage (BAL) including fungal culture were negative. Given the lack of clinical improvement, an open lung biopsy was done, with pathology revealing blastomycosis. Immediately after surgery, the patient developed severe respiratory failure consistent with ARDS. Liposomal Amphotericin B treatment replaced antibiotics and intravenous methylprednisolone was continued.  The patient’s PaO2/FiO2 ratio gradually improved, and he was successfully extubated one week later. Methylprednisone was tapered, and converted to oral prednisone. The patient will be on liposomal amphotericin for 28 days and itraconazole for one year thereafter.

Discussion: Our case presented an unusual diagnostic challenge with Blastomycosis. In one case series, 100% of cultures obtained from bronchoalveolar lavage yielded the organism in patients who were known to have pulmonary blastomycosis. In our case, the bronchial washing fungal culture and smear were negative. The diagnosis was only made after the lung biopsy. Moreover, blastomycosis infrequently presents as Acute Respiratory Distress Syndrome, especially in immunocompetent patients. In previous case reports, blastomycosis-related ARDS cases were associated with a mortality rate of 50-89%, when antifungal therapy without adjunctive corticosteroids treatment regimen was employed. In contrast, two case reports show better efficacy when corticotherapy is combined with antifungal therapy. It is presumed that corticotherapy reduces inflammation, a core component of ARDS. In fungal infections, inflammation is likely secondary to host cell mediated immunity, and it is proposed that steroids subdue such a reaction and therefore, increase gas exchange. 

Conclusions: Blastomycosis can present in a myriad of forms and may pose a diagnostic challenge. Although bronchoalveolar washings are associated with a high yield in identifying blastomycosis, if there is a high clinical suspicion, a negative bronchoalveolar lavage should warrant immediate lung biopsy to avoid delay in diagnosis and subsequent treatment. Blastomycosis infrequently present as ARDS and in such cases, corticotherapy in adjunction to antifungal therapy should be strongly considered.