Core needle biopsy of periacetabular chondrosarcoma often results in undergrading but does not change management by...

There is discrepancy in the histologic concordance of pre-operative biopsy grading and post-surgical resection grading of periacetabular chondrosarcoma. This discrepancy poses a question as to whether the chosen treatment should depend upon on the initial assessment of the tumor grade. This is a retrospective review of patients with periacetabular cartilaginous tumors who were treated between the years 2000 and 2022 at a single institution. All patients included in the analysis underwent surgical resection. The pre-operative biopsy and post-surgical resection histological grades were compared. Concordance and treatment implications were evaluated. Twenty-two pre-operative Image Guided Core Needle Biopsies (IGCNB) were performed. There was concordance between pre-operative and surgical resection histological grade in only 9 cases, giving a (9/22) 40.9% accuracy rate. In total there were 13 cases of discrepancy between pre-operative biopsy and surgical resection regarding histological grade. In 12 cases of discrepancy, surgical resection histopathology revealed a higher grade than that of pre-operative biopsy histopathology. In one case of discrepancy, pre-operative IGCNB biopsy histology revealed a high-grade chondrosarcoma while the surgical resection histology revealed an intermediate-grade. There were no situations in which the plan made based on a preoperative biopsy resulted in an inappropriate treatment decision, even when there was not concordance between preoperative diagnosis and diagnosis after definitive resection. Significant discrepancy in grading was observed with pre-operative IGCNB of periacetabular cartilaginous lesions. However, while 12 out of the 13 discordant cases (92.3%) underestimated the true grade of the tumor, there was no impact on appropriateness of the selected treatment, suggesting that accuracy of grade is not an important factor to consider in this location.