Abstract

Background Blastomycosis is a rare fungal infection caused by Blastomyces dermatitidis, which typically grows in wood and soil. The skin is affected in approximately 20-40% of cases. If not immediately recognized and treated, skin infections can progress to multiorgan disease, often involving the lung. The case fatality rate for disseminated blastomycosis was 78% prior to the availability of specific fungal therapy. Clinical Presentation A 53-year-old male presented with a 7-day history of multiple pruritic nodules and plaques on the left lower back and buttock without a known precipitating event. He reported his occupation to be in landscaping, specifically involving tree trimming. The physical examination revealed large exophytic plaques with surrounding erythema on the left buttock that occupied approximately 90% of the skin surface of this area. A shave biopsy was performed, and the histopathologic examination revealed pseudoepitheliomatous hyperplasia with an intraepidermal and dermal infiltrate composed of neutrophils, lymphocytes, histiocytes, eosinophils, and multinucleated giant cells with granuloma formation, as well as the presence of broad-based budding fungal organisms, morphologically consistent with Blastomyces dermatitidis. The fungal culture confirmed the diagnosis. The patient was started on a 6-to-12-month course of itraconazole. Conclusion This case highlights the clinical and pathologic manifestations of cutaneous blastomycosis and stresses the importance of early diagnosis of these lesions to aid in preventing systemic involvement.

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