• Seven cases are presented to illustrate the importance of recognizing benign lesions or normal conditions that may give the appearance of malignant bone tumors. Any single lesion should be studied from more than one angle, and the roentgen appearance should be watched over an interval of time. Examination of the entire skeleton is necessary for exact diagnosis.
In five cases the conditions were found to be either normal or self-limited, so that no operation was required. A sixth case concerned a lymphoblastoma that regressed almost completely after radiotherapy and nitrogen mustard administration; the seventh was a giant-cell tumor successfully treated by amputation. A systematic approach to differential diagnosis gives the patient the advantage of conservative treatment and spares him mental trauma.