A Blastomycosis dermatitis with only skin manifestations: a case report

Background and objective Infections caused by Blastomyces dermatitidis can usually affect nearly every organ in the body, including the lungs, skin, bones, and genitourinary system. Methods We present a case of a 33-year-old Chinese male who developed Blastomyces dermatitidis infection with solely skin involvement one year after returning from the United States. Results The patient initially presented with verrucous plaques on his face and occipital region, which were misdiagnosed as common wart. Comprehensive blood tests, including assessments of complete blood count, liver function, kidney function, T lymphocyte subset count, G-test (1,3-β-D-glucan test), GM-test (Galactomannan test), and Cryptococcus test ( Cryptococcal capsular polysaccharide antigen test), all returned normal results. Fungal culture and molecular sequencing confirmed the organism’s identity as Blastomyces dermatitidis . The patient was treated with Itraconazole, and the verrucous plaques resolved without recurrence of facial rashes. Conclusion This case highlights the importance of considering Blastomyces dermatitidis infection in patients with a history of residence in endemic regions and unexplained skin lesions, even without respiratory symptoms or other systemic involvement.