Primary intraosseous manifestation of Rosai-Dorfman disease: 2 cases and review of literature.

Rosai-Dorman disease (RDD) is a rare disorder of proliferative histiocytes with an unknown etiology. It is also known as sinus histiocytosis with massive lymphadenopathy. Most patients present with painless cervical lymphadenopathy due to accumulation of histiocytes in the lymph nodes, often in conjunction with fever, elevated leukocyte count and erythrocyte sedimentation rate. Isolated skeletal involvement is very rare.