Sonographic evaluation of a tibial periosteal ganglion with an intraosseous component.

periosteal ganglion cyst is a rare condition that can easily be misdiagnosed as other types of surface bony lesions because of cortical erosion and suggestive periosteal reactions on plain radiography. We encountered a periosteal ganglion located over the anterolateral aspect of the metaphysis of the distal tibia, which was connected to an intraosseous ganglion cyst through a cortical defect on the anterolateral surface of the distal end. To our knowledge, such a case has not been reported previously. We present the sonographic features and the magnetic resonance (MR) imaging and computed tomographic (CT) findings of this case. Overall, sonography can be used to characterize the location and cystic nature of a periosteal ganglion.