股関節内に発生した類骨骨腫のMRI診断

抄録

Osteoid osteoma is a relatively common bone tumor of benign origin and can be easily diagnosed. However, when intraarticular lesions occur, they may pose a diagnostic challenge. Recently, we experienced a rare case of osteoid osteoma in the hip joint of a fifteen-year-old girl and describe the method of diagnosis and treatment.
She complained of right hip pain and restriction of motion without any history of trauma or joint disease. The pain was aggravated by motion and she also had night pain. There was no findings on initial roentgenogram, however, two months later roentgenogram had showed a calcified mass in the acetabular fossa. MR imaging in early phase showed only localizad hypertrophic synovium with slight joint effusion. However, Gadolinium (Gd) enhanced MR imaging revealed a ringed area of low signal intensity around a calcified mass. A bony mass covered with synovium was observed in the acetabular fossa using an arthroscope and the mass was excised. Histopathologically itwas diagnosed as a osteoid osteoma with a nidus.
From this study it can be suggested that Gd enhanced MR imaging is useful for the accurate diagnosis of intraarticular Osteoid osteoma.