MR findings of Erdheim-Chester disease.

Lipoid granulomatosis (Erdheim-Chester disease) is a rare but distinct form of histiocytosis. This disease has characteristic radiologic findings involving the musculoskeletal system that are critical to the diagnosis: symmetric sclerosis of the metaphysis and diaphysis of long bones with relative sparing of the epiphysis as depicted on conventional radiography. However, it is a systemic disease that involves multiple organ systems. This pictorial essay is of a single patient imaged over multiple years, using various pulse sequences with both low and high field strength MR scanners. It depicts many of the characteristic findings encountered in this rare systemic disorder.