Intraosseous pneumatocyst of the ilium: CT findings in two cases and literature review.

Intraosseous pneumatocyst of the ilium is a rare lesion of uncertain origin. It predilects male subjects and may be associated or not with sacroiliac joint degenerative disease, intra-articular gas, sacral pneumatocyst, and communication with the articular space. To our knowledge, only 16 observations have been reported in the literature. We have evaluated with plain radiographs and CT two additional cases. Plain films frequently identify these lesions, but CT is the method of choice in demonstrating their air density and assessing the possible abnormalities of the surrounding bone and sacroiliac joints.