Destructive Bone Lesions

Abstract

(Pseudocysts, Encroachments, Erosions, Destructions, Lysis, and Fractures) Pseudocysts on the hands and feet are common findings in rheumatoid arthritis. They are rarer in the cervico-occipital region, except perhaps for the odontoid process. Some of the pseudocysts correspond to encroachments seen on frontal views, others are intraosseous cavities. They occur early, are rounded or oval-shaped, and usually multiple and rather small. When they extend, they are poorly outlined and may be surrounded by osteosclerosis when they become coalescent. Small constitutional pseudocysts may be seen in the lateral masses of the atlas but they never have the same blurred aspect with now and then interrupted or condensed margins. Diffuse de-mineralization and eventual narrowing of the atlanto-occipital or lateral atlantoaxial interspaces are arguments in favor of poly-arthritic pseudocysts.