Blastomycosis can present in a number of ways, from a mild case which present much like influenza and resolves itself within a few weeks, to Acute Respiratory Distress Syndrome (ARDS), which progresses quickly and is most often fatal if untreated. Because of the similar symptoms, blastomycosis is often mistaken for histoplasmosis, another fungal disease. Blastomycosis is not easy to confirm. It will often grow in blood cultures or sputem cultures, but will not necessarily do so. A lung biopsy is often definitive.