Successful voriconazole therapy after itraconazole hypersensitivity in cutaneous blastomycosis

Background: Blastomycosis is a fungal infection caused by Blastomyces spp, typically presenting with pulmonary involvement in endemic regions. Cutaneous involvement is the most common extrapulmonary manifestation and can pose a diagnostic challenge, especially in non-endemic areas. Methods: We describe a case of a previously healthy 31-year-old man presenting to an emergency department in Vancouver, British Columbia, with a chronic, draining skin lesion in the posterior left auricular region. Results: The patient had a remote history of travel to endemic regions, including Kenora and Thunder Bay, Ontario, Canada. Despite multiple courses of antibiotics, the lesion persisted. Diagnosis of cutaneous blastomycosis was confirmed by tissue biopsy and fungal culture, with compatible histopathology, although urine antigen testing was negative. Treatment was initially attempted with itraconazole, but the patient developed a delayed cutaneous hypersensitivity reaction. Therapy was successfully switched to voriconazole, resulting in clinical resolution of the lesion without recurrence of allergic symptoms. Conclusion: This case highlights the importance of obtaining a detailed travel history for patients with persistent cutaneous lesions. Furthermore, it demonstrates that voriconazole is a safe and effective alternative for treating blastomycosis in patients who develop hypersensitivity to itraconazole.