Radiologic diagnosis of Erdheim-Chester disease. A case report

Erdheim-Chester disease is a rare disorder, belonging to the group of histiocytoses, in which diffuse infiltration of histiocytes affects various organs and systems. Bone involvement in Erdheim-Chester disease manifests as generalized sclerosis of the bone marrow and cortex of the long bones, and this peculiar radiologic characteristic differentiates it from other histiocytoses. Diagnostic suspicion of the disease derives from the pulmonary and bone radiologic findings as well as from the clinical findings. Histological study reveals histiocyte infiltration affecting the soft tissues, musculoskeletal system, and central nervous system. The definitive diagnosis is reached by immunohistochemistry. Like other histiocytoses, such as Langerhans cell histiocytosis, immunohistochemical techniques reveal lipid-laden histiocytes; however, unlike the other types, Erdheim-Chester histiocytes stain negatively for S 100 protein and do not contain Birbeck granules.