Rosai-Dorfman disease of the central nervous system: report of 6 cases and review of the literature.

Rosai-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy (SHML), is an uncommon benign idiopathic lymphoproliferative disorder. The histologic hallmark of RDD is the finding of emperipolesis displayed by lesional histiocytes. 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. As a result, therapeutic approaches to CNS involvement in RDD are not well established. Herein we report 6 cases of RDD with isolated CNS involvement and review the literature on RDD with CNS involvement. One of the presented cases exhibited intramedullary involvement of the spinal cord--a very rare form of RDD with CNS involvement.