Concordance of histopathological and radiological grading in soft tissue sarcomas

Abstract

Aim: The grade of the tumor is essential for planning the treatment strategy in soft-tissue sarcomas (STS). The goal of this study is to determine magnetic resonance imaging features related to histopathological grade and aggressiveness of STS. Material and Method: This retrospective single-center study involved preoperative contrast-enhanced MRI examinations of 64 patients with STS. MRI findings evaluated were; heterogeneity, necrosis, hemorrhage, and relationship with surrounding tissue in T1-weighted (T1W), T2-weighted (T2W), and T1W post-contrast sequences of the lesion. Histological grade was determined with the Fédération Nationale des Centres de Lutte Contre Le Cancer (FNCLCC) grading system, and the aggressiveness of the lesion was measured with the Ki-67 index. Results: Sixty-four patients (mean age 45.5±21.6, M/F ratio 34/30) with STS were included. 33 (51.6%) patients graded as FNCLCC grade 3. On MRI examinations, the absence of necrosis was significantly associated with FNCLCC grade 1 and a low Ki-67 index (p<0.001). The presence of hemorrhage signal distinguished as a hyperintense signal on T1W, tail sign, and post- contrast peritumoral enhancement was significantly higher in FNCLCC grade 3 soft tissue sarcomas (p:0.008, p:0.001, p:0.004, respectively). The presence of peritumoral edema on T2W imaging in all high-grade patients also showed a strong relationship between these two (p:0.001). Conclusion: Our study found that the presence of hemorrhage signal, tail sign, peritumoral enhancement, clear borders of 50% and less obtained from conventional MRI features of soft tissue sarcomas are associated with high grade tumors. The absence of necrosis signal, clear borders of 90% and above in MRI were significantly associated with FNCLCC grade 1.