Unusually located osteoid osteomas.

The files of 12 patients (aged 12-33 years) with an equal number of surgically proven osteoid osteomas (OOs) were reviewed in attempt to find a diagnostic algorithm in cases of unusually located OOs. Plain radiography (PR) and thin collimation computed tomography (CT) had been performed in all patients, while bone scintigraphy (BS) had been performed in eight and magnetic resonance imaging (MRI) in two. The OOs were located at juxta- or intra-articular sites, except for one located at the left neck of the L4 vertebra.

MRI of eosinophilic granuloma.

The imaging studies of nine histologically proven eosinophilic granulomas were reviewed. Radiographs and MRI studies were performed on all patients, with eight patients being examined by bone scintigraphy and six by CT. Matrix calcification, not evident on radiography, was demonstrated in two cases by CT.