Lesion of the distal radius A well-circumscribed expansile lesion is noted within the distal metaphysis of the radius approaching but not involving the epiphysis. The mass measures 4.4 x 2.9 x 3.1 cm in the greatest craniocaudal, AP, and transverse dimensions. There is thinning of the posterior medial cortex with irregularity likely relating to prior fracture. On T2 sequences, the lesion demonstrates numerous fluid-fluid levels and there is a small amount of reactive muscle edema and enhancement. Following contrast administration, there is diffuse thinning septal enhancement with areas of slightly thicker enhancement (series 13, images 22 and 24 of 34).
Expansile mass within the distal radius demonstrates imaging characteristics most compatible with aneurysmal bone cyst.