Core Needle Biopsy Of Periacetabular Chondrosarcoma Often Results In Undergrading But Does Not Change Management By Experienced Orthopaedic Oncologists

Abstract Background There is discrepancy in the histologic concordance of pre-operative biopsy and post-surgical resection grading of periacetabular chondrosarcoma. This discrepancy poses a question as to whether the treatment may differ depending on the initial assessment of the tumor grade. Methods 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. Results Of the 23 preoperative biopsies performed, there were 19 Image Guided Core Needle Biopsies (IGCNB), three Fine Needle Aspirations (FNA), and one open biopsy. There was concordance between pre-operative and surgical resection histological grade in only 10 cases using all methods of biopsy (IGCNB, FNA, and open biopsy), giving a (10/23) 43.5% accuracy rate. When considering biopsy techniques individually there was an accuracy rate of 7/19 (36.8%) for IGCNB, 2/3 (66.7%) for FNA, and 1/1 (100%) for open biopsy. 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 histology revealed a higher grade than that of pre-operative biopsy histology. 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. Conclusions Significant discrepancy in grading was observed with pre-operative IGCNB and FNA 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 treatment decision making.