Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease).

Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) is a unique disease of unknown etiology with a childhood predilection. Reports have established the worldwide distribution of the disorder. Although peripheral lymphadenopathy is the most common mode of presentation, numerous studies and individual case reports have established the fact that 30-40% of affected individuals have extranodal manifestations particularly in the head and neck region where the adenopathy tends to be concentrated. As yet, the pathogenesis of SHML has not been established but speculation relates the disorder to an aberrant response to an unspecified antigen, possibly an infectious organism. Because of the clinical manifestations, the radiographic features of SHML are not pathognomonic but rather engender a differential diagnosis which includes lymphomatous, pseudolymphomatous and infectious conditions. Appropriate imaging of patients with SHML depends upon presenting symptoms and signs. Radionuclide bone scanning may be helpful in the evaluation of suspected skeletal lesions or joint symptoms. Gallium scanning is often positive in nodal disease and CT, MRI and sonography are helpful in the evaluation of extranodal sites of involvement such as the orbit, eyelid, upper aero-digestive tract and retroperitoneum.