Nondiaphyseal osteoid osteomas in the pediatric patient.

Nondiaphyseal osteoid osteomas lack the classic roentgenographic appearance of diaphyseal lesions. This may delay diagnosis and treatment. This paper reports on seven children with nondiaphyseal osteoid osteoma seen consecutively. Delay in making the diagnoses, once the children were examined by orthopedic surgeons, averaged six months. Absence of the classic roentgenographic appearance led to the delay in these cases. The difficulty in diagnosing the lesion on routine roentgenograms derives from the specific reaction to the lesion by cancellous bone as compared to cortical bone. Bone scans proved to be sensitive at locating a focal area of intense uptake but lacked the specificity to make the diagnosis. Computed tomography (CT) was quite specific at making the diagnosis and localizing the lesion for biopsy. How to differentiate between osteoid osteoma and osteomyelitis by CT is described. When osteoid osteoma is suspected in nondiaphyseal locations, CT is likely to aid in the diagnosis and localization of the lesion for biopsy.