Intraosseous pneumatocyst of the iliac bone.

Intraosseous pneumatocyst of the iliac bone is usually an innocuous incidental finding with characteristic radiographic features. Because this entity is uncommon and has not been described in the orthopaedic literature, many orthopaedic surgeons are unfamiliar with the entity. Three cases of intraosseous pneumatocyst of the iliac bone are presented to illustrate some of the imaging features to assist in recognizing it for what it is: an innocuous incidental finding that should not prompt invasive procedures such as a biopsy.