Meningeal Rosai-Dorfman disease mimicking meningioma.

Rosai-Dorfman disease of the central nervous system is extremely rare and difficult to diagnose also for pathologists. We describe three unusual cases of meningeal Rosai-Dorfman disease and illustrate the difficulties of preoperative and pathological diagnosis. We retrospectively analyzed three patients who underwent surgery for a suspected meningioma for whom the final diagnosis was Rosai-Dorfman disease of the central nervous system. Pathological initial diagnosis was schwannoma, lymphoplasmacyte-rich meningioma, or inflammatory tumor, but final diagnosis in all cases was Rosai-Dorfman disease. These cases underline the preoperative and pathological difficulties of such diagnosis. Pathologists and physicians should be aware of the occurrence of such rare localization of this disease and should think about this differential diagnosis in lymphocyte-rich meningeal tumors mimicking, clinically and radiologically, a meningioma. Communication of significant previous medical history to pathologists and careful examination of slides with appropriate medical history and the use of S100 antibody in the diagnosis of meningeal tumors mimicking Rosai-Dorfman disease could lower the rate of misdiagnosis.