Polymorphous meningitis with atypical mononuclear cells in Sjögren's syndrome.

Central nervous system complications in Sjögren's syndrome have been reported sporadically for years. We examined the nature and frequency of central nervous system abnormalities in 11 patients with clinically documented Sjögren's syndrome on whom postmortem examination was performed. In 9, characteristic mixed (polymorphous) inflammatory infiltrates containing large atypical mononuclear cells were observed in the leptomeninges, choroid plexus, or both; only 5 of the 9 neurological symptoms, however. Among patients with central nervous system lesions, 3 had definite vasculocentric inflammation and 1 had a necrotizing vasculitis with extensive subarachnoid hemorrhage. Four patients had evidence of chronic subarachnoid microhemorrhage associated with polymorphous meningitis. Atypical mononuclear cells in a polymorphous inflammatory exudate were observed in antemortem cerebrospinal fluid cytological specimens from 2 of the patients. The findings suggest that central nervous system involvement in Sjögren's syndrome is common and that neurological symptoms are related to polymorphous meningitis and vasculitis. Detection of atypical mononuclear cells in cerebrospinal fluid specimens may be of diagnostic value.