[Erdheim-Chester disease].

In this review the authors focus on Erdheim-Chester disease, a rare systemic disorder of unknown etiology, likely neoplastic, characterised by xantogranulomatous infiltrates of foamy, lipid-laden histiocytes in all involved sites, principally bone, retroperitoneum, lung, pleura, pericardium, retroorbital tissue and brain; moreover periadventitial tissue of the aorta and major arteries may be present. The clinical picture and the course are very various. Erdheim-Chester disease belongs to histiocytosis and differs from Langerhans' cell histiocytosis for clinical, histologic and immunohistochemical features. After the observation of 2 cases we have reviewed the literature; we think useful to present the principal features of the disease, which is likely more frequent than expected; Erdheim-Chester disease is rarely diagnosed because of the poor knowledge of the disease, which is not reported on the common textbooks of medicine.