Rosai-Dorfman-Destombes Disease

**Semantic type:** Neoplastic Process

**Definition:** A rare histiocytic disorder of unknown etiology, characterized by distention of the lymph node sinuses and sinusoidal histiocytic infiltration. The histiocytes characteristically contain ingested lymphocytes and are S100 and CD68 positive, and CD1a negative. Patients present with cervical lymphadenopathy, fever, leukocytosis, and hypergammaglobulinemia. It can affect extranodal sites, including skin, bones, and the respiratory tract. It occurs in isolation or may be associated with autoimmune disorders or malignancies. Mutations in NRAS, KRAS, MAP2K1, and ARAF genes have been identified in affected tissues, suggesting a clonal origin in some cases. It is a self-limited disorder, although some patients may have a poor prognosis.

**Synonyms:** - Destombes-Rosai-Dorfman Disease - RDD - Rosai-Dorfman Disease - SHML - Sinus Histiocytosis with Massive Lymphadenopathy