Preoperative Factors Associated with Infiltrative Histologic Growth Patterns in Extremity Soft Tissue Sarcoma

Abstract

Soft tissue sarcoma (STS) with an infiltrative histologic growth pattern, when compared to STS with an expansile pattern, may pose difficulties in local control. Preoperative assessment of the presence of infiltrative histologic growth pattern would be helpful in deciding treatment strategies. A review of 144 patients who underwent surgery for extremity STS was performed. Microscopically, the histologic growth pattern was defined as infiltrative if the penetration of the tumor cells into the surrounding tissue was observed. Possible clinicopathologic factors that might be associated with infiltrative histologic growth pattern were investigated with regard to patient demographics, tumor characteristics, and MRI findings. Of the 144 tumors, 71 (49%) showed infiltrative histologic growth pattern. On multivariate analysis, histological subtypes other than liposarcoma (OR = 4.57, p = 0.02) and infiltrative border on MRI (OR = 2.48, p = 0.01) were independent factors associated with infiltrative histologic growth pattern. Predictive index based on these two factors showed a significant improved accuracy (ROC-AUC = 0.647) for predicting infiltrative histologic growth pattern compared to either factor alone. Our data suggests that liposarcoma histology and tumor border on MRI can predict histologic growth pattern in extremity STS.

Figure 1

Representative sections of histologic growth pattern. Photomicrograph and MRI ((a) gross, (b) gadolinium-enhanced T1-weighted sequences with fat suppression, and (c) H&E staining, magnification ×1) of the histological specimen of an subcutaneous synovial sarcoma with expansile growth pattern. Photomicrograph ((d) gross, (e) gadolinium-enhanced T1-weighted sequences with fat suppression, and (f) H&E staining, magnification ×1) of the histological specimen of a subcutaneous undifferentiated pleomorphic sarcoma with an infiltrative growth pattern.

Figure 2

Representative images of different tumor borders on MRI. (a) T1 enhanced MRI of an intramuscular synovial sarcoma with pushing border on MRI. (b) T1 enhanced MRI of an intramuscular undifferentiated pleomorphic sarcoma with infiltrative border on MRI with the tail sign. (c) T1 enhanced MRI of a leiomyosarcoma with infiltrative border on MRI without the tail sign.

Figure 3

Pairwise AUC comparison of the predictive index and the tumor border on MRI alone or histological subtype other than liposarcoma alone in predicting infiltrative histologic growth pattern. (a) Pairwise area under the receiver-operating curve (AUC) comparison of the predictive index and the tumor border on MRI alone in predicting infiltrative histological growth pattern. (b) Pairwise area under the receiver-operating curve (AUC) comparison of the predictive index and histological subtype other than liposarcoma alone in predicting infiltrative histological growth pattern. AUC, area under the curve. The dashed line in both graphs represented random guess to predict (AUC = 0.500).