Blastomyces dermatitidis is typically contracted through inhalation of the dimorphic conidia, resulting in pulmonary infection as well as extrapulmonary disease through hematogenous spread. Blastomycosis is considered one of the great mimickers in medicine, with verrucous cutaneous blastomycosis resembling skin malignancy and B dermatitidis pulmonary infections often confused with lung cancer. Cutaneous blastomycosis can also often mimic pyoderma gangrenosum and should be considered in the differential diagnosis in any suspected case. This case involves a cutaneous blastomycosis lesion of the leg that was initially diagnosed as squamous cell carcinoma, which was excised. Within a month, the atypical lesion recurred in the area and was unresponsive to antibiotic therapy, rapidly progressing in size and inflammation. We discuss the eventual diagnosis of this blastomycosis infection and the importance of ruling out cutaneous blastomycosis when managing pyoderma gangrenosum.
Keywords: Blastomyces dermatitidis; blastomycosis; cutaneous; fungal; infection; squamous cell carcinoma.