Erdheim-chester disease.

Erdheim-Chester disease (ECD) is a rare histiocytic infiltrative disease, characterized by long bone sclerosis. We describe two confirmed cases of ECD, both of which demonstrate non-malignant retroperitoneal and peri-renal infiltration causing dilatation of the upper renal tracts. The cases are illustrated with contrast studies, computed tomography (CT) and magnetic resonance imaging (MRI). Typical sclerosis of the long bones was apparent on radiography. Both cases have been treated conservatively to date.A brief review of the literature regarding the manifestations of ECD is included. In cases of non-malignant retroperitoneal infiltration, ECD should be considered as a diagnosis and radiographs of the long bones performed.