Disseminated Blastomycosis: A Case of Multisite Infection in an Immunocompetent Patient

BACKGROUND Blastomycosis is a fungal infection caused by Blastomyces spp., a dimorphic fungus hyperendemic in Wisconsin, USA. CASE REPORT A 54-year-old previously healthy man presented with right foot and thigh pain, erythema, and a non-healing purulent ulcer on the right buttock. Initial treatment with oral doxycycline and cephalexin was unsuccessful, and subsequent imaging revealed a thigh hematoma and acute osteomyelitis of the forefoot with an adjacent abscess. The patient underwent 2 incision-and-drainage procedures, which uncovered a disarticulated second toe and persistent purulence. Histopathologic examination of the amputated toe showed multinucleated giant cells and thick-walled yeasts with broad-based budding, consistent with Blastomyces spp. Antifungal therapy with itraconazole was initiated. Fungal cultures from the gluteal abscess confirmed the diagnosis. Chest CT revealed diffuse pleural nodules and tree-in-bud opacities in the left upper lobe, indicative of pulmonary involvement. The patient completed a 12-month course of itraconazole with full resolution of infection and no complications. CONCLUSIONS Blastomycosis typically presents as a pulmonary infection but may disseminate to the skin and bones. Unlike other endemic fungal infections such as histoplasmosis or coccidioidomycosis, which more often disseminate in immunocompromised individuals, blastomycosis can affect immunocompetent hosts. This case highlights the importance of considering blastomycosis in patients from endemic regions who present with cutaneous or osteoarticular infections unresponsive to antibacterial treatment, regardless of their immune status.