Histologic review demonstrated moderate multifocal subacute vasculitis and nonsuppurative encephalitis. Infl ammatory lesions of the central nervous system were focused in gray matter of the medulla oblongata, pons, mesencephalan, and cerebellum. Lesions were bilateral but more severe on the right side. Meninges demonstrated moderate focally extensive and multifocal areas of acute meningeal congestion and hemorrhage. Mild multifocal lymphocytic infi ltrates expanded the leptomeninges. Blood vessels demonstrated mild to moderate acute necrosis and lymphocytic and contained plasmacytic and neutrophilic infi ltrates within vascular walls. Encephalitis was characterized by perivascular lymphocytes and fewer plasma cells expanding the Virchow-Robbins spaces. Small, scattered, perivascular ring hemorrhages were noted. A few multifocal loosely arranged glial nodules were within cerebral white matter.