We present the case histories of five patients with Erdheim-Chester di
sease, a rare lipoidosis that has several typical radiographic feature
s. In all the patients, the diaphyses and metaphyses of the extremitie
s demonstrated a symmetric pattern of diffuse or patchy increased dens
ity, a coarsened trabecular pattern, medullary sclerosis, and cortical
thickening. The epiphyses were spared in four patients and partially
involved in one. The axial skeleton was involved in one patient. Radio
tracer Te-99m accumulated in areas of radiographic abnormalities in al
l patients. In one patient, MRT demonstrated an abnormal signal, corre
sponding to radiographic abnormalities. The signal was hypointense to
muscle on T1-weighted sequences and heterogeneously hyperintense and h
ypointense to normal bone marrow on T2-weighted sequences. Xanthogranu
lomatous lesions infiltrated the retroperitoneum in one patient, the t
estes in one patient, the eyelids in one patient, and the orbits in tw
o patients.