Extraosseus Ewing sarcoma: An uncommon periclavicular location

A rapidly enlarging right sternoclavicular mass in a young male was labeled as a nonspecific mass. MRI played a crucial role in characterizing the lesion, helping to define the possible mesenchymal origin and the relative involvement of the surrounding structures. We also discuss the differential diagnosis of an extraosseus Ewing sarcoma (ES), with its imaging findings.