What are the key imaging features and clinical presentations of brain blastomycosis, and how does it typically manifest in endemic regions like the Ohio and Mississippi River valleys?

Brain blastomycosis occurs predominantly in the Ohio and Mississippi River valleys. It often presents with meningitis, while parenchymal abscesses and granulomas are less common. Key imaging features include ring-enhancing lesions on MRI, which can mimic neoplasms or other infectious processes. Epidural granulomas and abscesses may result from direct extension from bone infection. A clinical pearl is that blastomycosis can mimic tuberculosis or malignancy, leading to diagnostic delays.