Extranodal Rosai-Dorfman disease of bone, subcutaneous tissue and paranasal sinus mucosa with a review of its pathogenesis.

We report an unusual case of extranodal Rosai-Dorfman disease presenting in a 36-year-old man with lesions of bone, subcutaneous tissue of the arm and maxillary sinus mucosa unassociated with lymphadenopathy or systemic symptoms. These lesions appeared metachronously within a 6-month period. The diagnostic light microscopic and immunohistochemical findings and pathogenesis of this interesting disease are discussed.