ABSTRACT
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. The diagnosis based on the MRI examinations was synovitis. BS showed increased accumulation of the radioisotope at the site of the lesions, without the 'double density' sign. PR showed the nidus of OO in only six patients, whereas CT located the nidus in all patients. In conclusion, we believe that when an OO is clinically suspected at an unusual location, CT should be performed in all cases, even when a lesion is depicted by PR and BS, because CT will not only locate the nidus but will also provide a precise anatomy of the area around the nidus and help in therapeutic decision making and surgical planning. MRI can be misleading and must not be used in the initial assessment of a possible osteoid osteoma.
Subject(s)
Acetabulum , Acromion , Bone Neoplasms/diagnosis , Femoral Neoplasms/diagnosis , Humerus , Metatarsus , Osteoma, Osteoid/diagnosis , Radius , Talus , Tibia , Tomography, X-Ray Computed , Acetabulum/diagnostic imaging , Acromion/diagnostic imaging , Adolescent , Adult , Bone Neoplasms/diagnostic imaging , Child , Evaluation Studies as Topic , Female , Femoral Neoplasms/diagnostic imaging , Femur Head/diagnostic imaging , Femur Neck/diagnostic imaging , Humans , Humerus/diagnostic imaging , Magnetic Resonance Imaging , Male , Metatarsus/diagnostic imaging , Osteoma, Osteoid/diagnostic imaging , Radionuclide Imaging , Radius/diagnostic imaging , Talus/diagnostic imaging , Tibia/diagnostic imagingABSTRACT
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. MRI proved superior to both the radiographs and CT in defining the medullary extent of the lesion and the surrounding soft tissue changes. In eight of nine cases, on STIR sequences, an endosteal rim of low signal intensity surrounding the main lesion was present and may be an early feature of healing. The degree of peritumoral oedema accompanying eosinophilic granuloma was less extensive than that seen in either Ewing's sarcoma or osteomyelitis. The presence of both a low signal endosteal rim and limited peritumoural oedema on STIR sequences may be a useful indicator to the diagnosis of underlying eosinophilic granuloma.