[A patient with primary angiitis of the central nervous system: relation between MRI and pathological findings].

A 74-year-old woman, noticed sudden onset of quadriparesis when getting up in the morning on July 17th, 1992. At admission, she presented mild weakness of the limbs bilaterally, and deep tendon hyperreflexia, which were improved after about 4 hours. Serum and urinary laboratory examinations revealed no abnormal findings. Cerebrospinal fluid showed increased cells (75/mm3), and protein (58 mg/dl). Computed tomography revealed multiple low density lesions in the frontal, parietal, and occipital cortex. Magnetic resonance imaging showed low signal intensities on T1-weighted images and high signal intensities on T2-weighted images, suggesting tumorous lesions. On the gadolinium-enhanced images, the enhanced lesions were surrounded with low signal intensity. She developed hallucination and disorientation since around the 8th hospital day, and disturbance of consciousness at the 15th day, followed by coma, and she died from respiratory failure on the 17th hospital day. At autopsy, there were multiple small infarctions in the cerebral cortex and dark areas in the meninges, suggesting localized inflammation. On microscopical examination, remarkable proliferation of cells was seen at the small arteries of the leptomeninges and cerebral cortex. Parts of the vessels were replaced by multinucleated giant cells. No similar abnormalities were found in arteries in the other organs, except the central nervous system. The pathological diagnosis of primary angiitis of the central nervous system was made based on the above findings. The enhanced MRI findings were in excellent agreement with the pathological leptomeningeal vasculitis. The surrounding low intensity areas on the enhanced MRI were considered to reveal edematous change and infarction in the parenchymal lesions. We conclude that enhanced MRI is useful to make a diagnosis of CNS vasculitis.