Abstract
Erdheim-Chester syndrome, a non-Langerhans histiocytosis, is a very rare disease, in the present approximately 500 cases being reported in literature. It is characterized by the histiocytic infiltration of various organs and systems, therefore clinical signs and symptoms are miscellaneous. Despite that, there are a few patognomonic elements that help recognizing the disease: symmetrical involvement in the long bones of the lower limbs, bilateral perirenal infiltration (“hairy kidneys”) and circumferential aortic infiltration (“coated aorta”). However, in order to confirm the diagnosis, biopsy is required, histopathologic examination revealing “foamy” histiocytes. Currently, interferon alpha serves as the first line of treatment, most literature data showing that it might improve survival rate in patients diagnosed with Erdheim-Chester syndrome.