Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease)
Rosai-Dorfman disease (RDD) - sinus histiocytosis with massive lymphadenopathy - is a complex disease with variable clinical manifestations and course. The disease is extremely rare and difficult to diagnose. It is more incident in children and young adults, but generally can be presented at any age. The histological picture in RDD includes dilatation of the lymph sinuses because of accumulation of great numbers of S-100+ histiocytes with emperiopolesis signs; this phenomenon serves as the basic criterion for morphologic diagnosis. Extranodal involvement is found in 43% of patients with RDD and is characterized by diffuse infiltration of the organ tissue. A case with RDD is presented: a child aged 9 years with nodal and extranodal involvement.