Sacral Osteomyelitis With Abscesses and Fistulae: An Unusual Manifestation of Disseminated Blastomycosis

<i>Blastomyces dermatitidis</i>, the fungus responsible for blastomycosis, can cause systemic disease with clinical manifestations ranging from asymptomatic infection to acute or chronic pneumonia and extrapulmonary diseases. Here, we present a case of sacral osteomyelitis with multiple abscesses and a fistulous tract, which failed to improve after multiple courses of antibacterial therapy for presumed bacterial causes, leading to a significantly delayed diagnosis. Blastomycosis was diagnosed by potassium hydroxide (KOH) microscopy, fungal culture, and broad-range polymerase chain reaction (PCR). The patient was prescribed oral itraconazole, 200 mg three times a day for three days, followed by twice a day for one year. The presentation of abscesses and osteomyelitis with a fistulous tract in blastomycosis is uncommon, and one of the rare instances of dissemination and destruction of the sacral bone is being reported. The key to diagnosing the disease is considering it a possibility. Treatment depends on its severity.