Radiological Differences in Chondroblastoma of Tubular and Non-Tubular Bones

Abstract

Introduction: Chondroblastomas are rare bone tumours accounting for only 1% all primary bone tumours. Epiphysis of long bones are most commonly affected, where as the flat bones, short tubular bones and apophysis of long bones are comparatively less commonly affected. Aim: This study is aimed at finding out radiological differences when the tumour arises in tubular and nontubular bones. Materials and Methods: This retrospective study was conducted in the Department of Radiology, Nizam’s Institute of Medical Sciences, Hyderabad, India. All histologically confirmed cases of chondroblastoma were analysed with respect to their imaging findings. Results: Of the total 22 cases (including 13 females) that could be included in our study over seven years, 17 had lesions in long bones. Youngest was eight years old and the oldest was 40-year-old female. Four cases were associated with Anuerysmal Bone Cyst (ABC) and one case was associated with Giant Cell Tumour (GCT). Femur was the most common site (n=7) followed by tibia (n=7) and humerus (n=3). There were one each of calcaneum, talus, mandible, maxilla and iliac bone involvement. Epiphyseal lesions were seen 10 out of 17 tubular bones. Epiphyseal lesion extending to metaphysis were observed in seven. Typical site, geographic lucent lesion, matrix calcification and sclerotic rim were observed in 10 cases of long tubular bone and diagnosis was straight forward. Sclerotic rim, matrix calcification, periosteal reaction, coarse trabeculations and pathological fractures are common in lesions of long tubular bones. Soft tissue component is common in flat bone lesions. Tarsal bone lesions are most often associated with GCT/ABC and joint effusions. Conclusion: Chondroblastoma is more common in tubular bone and mostly around knee. About half of them show characteristic imaging features. Flat bone lesions are rare, show soft tissue component and appear aggressive. Tarsal bone lesions are mostly associated with GCT/ABC and joint effusion. Lack of calcification in non-tubular bones is characteristic and adds to the difficulty in diagnosing the tumour

Keywords

• aneurysmal bone cyst
• chondrosarcoma
• giant-cell tumour