Osteoid osteoma under the age of five years. The difficulty of diagnosis.

Ninety-one cases of histologically confirmed osteoid osteoma were collected during an 11-year period; of them, seven (7.6%) had onset of symptoms while younger than five years of age. Special diagnostic difficulties were found in this specific age group: most cases were misdiagnosed or diagnosed incorrectly. The time between the onset of symptoms and the diagnosis varied from three months to five years. Although pain was present in six patients, in four cases, other concomitant signs and symptoms attracted more attention and led to a misdiagnosis and unnecessary invasive procedures. Gait disturbance (limp) was the second most frequent sign and was always present when the lower extremity was affected. In five cases, initial radiographs were not conclusive. Bone scans were very sensitive and conclusive in three cases where radiographs were atypical. Computerized tomograms always located the tumor.