[Erdheim-Chester disease and Rosai-Dorfman disease: Pathological, radiological and clinical features of adult non-Langerhans cell histiocytosis].

Non-Langerhans cell histiocytoses (N-LCH) of adulthood are rare disorders with heterogeneous pathogenesis, morphology and clinical presentation. In this review two disorders are presented, which predominantly develop in extracutaneous sites in adults. Erdheim-Chester disease is a rare nonhereditary clonal disorder of lipid storing histiocytes most commonly presenting as osseous involvement of the long bones. Other organ manifestations include the central nervous system (CNS), the cardiovascular system, the retroperitoneum and kidneys and less commonly the skin and the lungs. Immunohistochemical staining reveals positivity for the macrophage markers CD163, CD68 and lysozyme but CD1a and langerin are negative, in contrast to Langerhans cell histiocytosis. Rosai-Dorfman disease is considered to be a reactive histiocytic proliferation occurring mainly in lymph nodes. Prominent sinuses filled with commonly multinucleated, S100-positive histiocytes with emperipolesis are a characteristic feature and develops particularly as extensive lymphadenopathy with massive sinus histiocytosis but can also occur extranodally. Painless bilateral cervical lymph node enlargement is the most common clinical presentation. This review summarizes the clinical, radiological and histopathological findings and discusses the recent molecular advances in these rare disorders.