Retrospective Study of Multimodality Imaging Features of Chondroblastoma.

ABSTRACT

Purpose: To evaluate the multimodality imaging features of chondroblastoma. Materials and Methods: Retrospective analysis of imaging features of 52 cases of histopathologically proven chondroblastoma from 2010 to 2022 was performed. Radiographs were evaluated for lesion site, location, morphology, margins, matrix mineralization, cortical breach, periosteal reaction, eccentricity, and subarticular extension. Appearance on T1, T2 weighted and post-contrast T1 was evaluated on MRI, with analysis of peritumoral edema and joint effusion. Results: Mean patient age was 18 years (10-57 years) with male preponderance (M = 39; F = 13). 75% (n = 39) cases involved an unfused skeleton and 25% (n = 13) affected a mature skeleton. Appendicular skeleton was involved in 88.5% (n = 46) cases and axial skeleton was involved in 11.5% (n = 6) cases with all cases involving epiphysis/epiphyseal equivalent. Radiographically, all cases were well-defined geographic osteolytic lesions with a narrow zone of transition, thin sclerotic rim and lobulated [56% (n = 29)] or smooth [44% (n = 23)] margins. Matrix calcification appreciable in 62% (n = 32) cases was 'fluffy/smudgy'. Chondroblastoma appeared isointense (83%, n = 43) on T1 MRI with characteristically low signal and hyperintense foci within (67%, n = 35) on T2-weighted images and post-contrast enhancement [heterogeneous lobular (88%, n = 46) or septal pattern (12%, n = 6)] with all barring three lesions showing perilesional edema. None of the cases of chondroblastoma in our study developed metastasis till last follow-up (mean 71 months). Conclusion: Chondroblastoma has distinctive imaging appearance and is often unlike majority other cartilaginous benign lesions due to characteristic low T2 signal on MRI and associated exuberant perilesional edema.