Oral fistula caused by Blastomyces dermatitidis

Blastomycosis is caused by the dimorphic fungus Blastomyces dermatitidis that primarily affects the lungs. Oral blastomycosis is uncommon and typically includes ulcers of the oral mucosa and/or the tongue. A 26-year-old woman from Manitoba, Canada, presented with a 3-year history of progressive swelling on the left side of the face. She had an oral ulcer and fistula associated with pain and difficulty chewing. She also had occipital and frontal headache, fatigue, and somnolence. Transoral biopsy and culture showed B. dermatitidis. She had no pulmonary fungal infection. Treatment with oral itraconazole resulted in complete resolution of all clinical symptoms and signs. Blastomycosis should be considered in the differential diagnosis of isolated oral lesions and fistulas in patients exposed to geographic regions endemic for B. dermatitidis. Antifungal treatment is recommended when specimens have confirmed the diagnosis.