[Tuberous cortical irregularity at the distal femoral metaphysis--an often malignancy pretending radiological finding (author's transl)].

Four juvenile patients are described who were referred to us because of a tuberous, irregularly demarcated cortical lesion at the dorsal surface of the distal femur metaphysis suspected to be a "malignant tumor". The histologic evaluation in three of these patients revealed a fibroplastic reaction of the periosteum with periosteal new bone formation and focal, partly also lacunar bone resorption by osteoclasts. During six months of observation there were no signs of further growing. No therapy was necessary. This tuberous cortical defect at the dorsal surface of the distal femur metaphysis has been found almost exclusively in children and juvenile persons. As causative agent an increased muscle power of the gastrocnemius muscles has been discussed at the site of its bone insertion. If the bone formative component prevails a tuberous proliferation is evident radiographically, however, if the fibroplastic reaction is predominant there is more evidence for a cortical defect. The resemblance of the tuberous cortical defects in the four patients discussed here with those cases described in the literature under various names is pointed out.