Review of sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) of head and neck

The entity known as sinus histiocytosis with massive lymphadenopathy (SHML) , or Rosai-Dorfman disease (RD disease), is an uncommon benign proliferatio n of hematopoietic and fibrous tissue that often presents in the head and n eck region. Its initial manifestations most often include a roughly symmetr ic, painless, bilateral cervical adenopathy, although extranodal disease ma y develop in a minority of patients. The key histologic feature of SHML is the presence of various numbers of large, pale histiocytic cells that conta in within their cellular borders apparently engulfed lymphocytes ("emperipo lesis"); these distinctive large, pale cells - RD cells - are S-100 protein -positive by immunostaining and so differ from ordinary histiocytes. Despit e its sometimes impressive clinical presentation, SHML is a benign and self -limited disease, whose treatment is aimed largely at controlling its local manifestations (most often by surgical therapy). The microscopic different ial diagnosis, particularly in extranodal disease, is at times challenging and can include Langerhans' cell histiocytosis, Hodgkin's disease, non-Hodg kin's lymphoma, metastatic carcinoma, and metastatic malignant melanoma.