[-The diagnosis of localized osteolysis-].

The diagnosis of localized osteolysis (synonym: bone cyst, defect) must be analytical. The site, size, and shape of the defect, its limits, assessed according to the Lodwick classification, reflect the activity of the lesion, the type of any periosteal reaction and the presence of a soft tissue mass are analysed successively. Based on these criteria and the clinical and laboratory characteristics, the image can be classified as quiescent or active, allowing guidance of management.