Erdheim-Chester Disease

**Semantic type:** Neoplastic Process

**Definition:** A very rare, multisystem non-Langerhans cell histiocytosis that predominantly affects adults. It is characterized by the proliferation in the tissues of lipid-laden macrophages and the presence of multinucleated giant cells. It results in sclerosis of the long bones and failure of the affected organs. Patients may present with bone pain, exophthalmos, ataxia, liver failure, kidney failure, and hypopituitarism.

**Synonyms:** - ECD - Lipogranulomatosis - Polyostotic Sclerosing Histiocytosis