Pseudomalignant osseous tumour

a nonmalignant tumour of soft tissue with sarcoma-like histologic features centrally and mature bone at the periphery. Most such tumours have been found in the extremities or gluteal region; however, lesions of the hands and feet show features similar to those of florid reactive periostitis. On radiographs the appearance is that of a well circumscribed ossifying mass with dense periphery and radiolucent centre. In some cases periostitis may be evident. The manifestations are identical to those of myositis ossificans traumatica, differing only in that persons with pseudomalignant osseous tumour usually do not have a history of trauma.