[Roentgenographic diagnosis of bone tumors--its basic knowledge and clinical application].

Roentgenographic diagnosis of bone tumors is considered to be extremely important to decide whether a new patient should be biopsied immediately to make the proper diagnosis or the patient could be followed up without operative treatment. The basis knowledge important in making the proper decision on the roentgenogram of the bone tumor, are presented and four cases of bone tumors or tumor-like conditions are presented to show how such knowledge becomes useful. First of all, the basic knowledge based on the anatomical peculiarities are described. Chordoma deriving from the remnant tissue, notochord, should be placed in the midline of the body. Metaphyseal region of the growing child showed a local immune deficient state because of the special anatomic arrangement of the vascular structure for the sake of the open epiphyseal line. This is thought to be related with the high rate of primary malignant bone tumors in this area and in this age group, for example, osteosarcoma. Next, roentgenographic changes are described separately: intracortical changes, cortical changes, periosteal reaction and soft tissue extension. These changes are summarized to differentiate the benign lesion from the malignant one. Thirdly, the peculiar location of the tumor is described. Examples are giant cell tumor, chondroblastoma and clear cell chondrosarcoma in the epiphyseal region, osteoid osteoma, intracortical abscess and the osteofibrous dysplasia in the intracortical region.