[Osteoid osteoma of the lower extremity].
Forty patients (27 males and 13 females) aged 18 months-41 years with preliminary diagnosis of osteoid osteoma localized within lower limb were reviewed. All underwent surgery. Histopathology confirmed previous diagnosis in 29 patients but in 11 cases (30%) histology either gave different diagnosis (despite clinical and radiological changes typical for osteoid osteoma) or was inconclusive. Three types of radiographic picture were distinguished: within cancellous bone the change was either osteolytic or oval, sclerotic; within cortical bone it was spindle-shaped, sclerotic. In 5 cases radiological symptoms were present prior to the pain. In 3 cases observed several years before surgery natural growth of osteoid osteoma could be traced. The key role of prostaglandin synthesized by osteoid osteoma in its pathology was emphasized.