Extranodal Rosai-Dorfman disease of bone and nose: a case report and review of literature.

Rosai-Dorfman disease (RDD) is a rare benign condition of unknown origin, which was first described in 1969. By histopathology, the disease is composed of sinusoidal lymph node hyperplasia and abundant histiocytes with haemophagocytosis, particularly lymphocytes. It commonly affects lymph nodes, and rarely has an exclusively extra-nodal clinical presentation. Among the so-called "extranodal" sites, the head and neck region, and in particular the nose and paranasal sinuses, are frequently affected. RDD shows a highly variable clinical course that can be partly modified by medical therapy. We present of a case of extra-nodal RDD, with nasal and osseous involvement, which has been followed-up for 19 years. We also discuss its presentation, the most relevant radiographic findings, treatment options and histological findings.