Fourth Ventricular Rosai-Dorfman Disease Mimicking Intraventricular Tumor in Young Adult: A Rare Case Report.

Rosai-Dorfman disease (RDD) or sinus histiocytosis with massive lymphadenopathy can present with or without systemic disease. It is a benign histioproliferative disorder characterized by generalized lymphadenopathy, weakness, anemia, and rarely extranodal involvement. While RDD most commonly affects lymph nodes, extranodal involvement of multiple organs has been reported, including the central nervous system (CNS). However, CNS involvement in RDD is rare and is not well characterized. Isolated involvement of the fourth ventricle is even rarer. Such lesions may be mistaken for intraventricular tumors such as ependymoma or medulloblastoma. This report highlights the necessity to consider RDD as a differential diagnosis in case of intraventricular space-occupying lesion.