Primary angiitis of the central nervous system: an ante-mortem diagnosis.

A rare case of primary angiitis of the central nervous system (PACNS) is reported with its clinical and magnetic resonance imaging (MRI) features. A 20-year-old girl presented with headache, projectile vomiting, unsteadiness of gait and urgency of micturition. She had left seventh nerve upper motor neuron type paresis, increased tone in all four limbs, exaggerated deep tendon reflexes, cerebellar signs, and papilloedema. Cerebrospinal fluid showed lymphocytosis with elevated protein and normal glucose level. Cerebral computerised tomographic scan and MRI showed bilateral diffuse asymmetric supra- and infra-tentorial lesions (predominantly in the supratentorial and left cerebrum). On MRI, the lesions were hyperintense on T2, and proton density-weighted images and hypointense on T1-weighted images. Based on the clinical findings of raised intracranial tension and MRI features, initial diagnoses of gliomatosis cerebrii, tuberculous meningitis, primary central nervous system lymphoma and chronic viral encephalitis were considered. PACNS was not included in the initial differentials and, an open brain biopsy was advised which established the definitive diagnosis.