Extranodal Rosai-Dorfman disease involving the meninges.

Rosai-Dorfman disease is an idiopathic histiocytic proliferative disorder characterized by sinus histiocytosis and massive lymphadenopathy. Extranodal involvement has also been reported. We report the case of a 57-year-old woman presenting with seizures, focal motor deficits, and leptomeningeal enhancement on magnetic resonance imaging. Meningeal biopsy revealed Rosai-Dorfman disease. Sinus histiocytosis may mimic meningeal disease, and Rosai-Dorfman disease should be considered in the differential diagnosis of dural-based masses with diffuse leptomeningeal enhancement.