It is recommended that classification of soft tissue sarcoma in the extremities and trunk wall is made according to WHO guidelines. Classification is under continuous development due to new diagnostic methods.
Malignancy grading is performed according to histological assessment of the tumor. A four-point scale has been commonly used until recently:
- grade I and II are low-grade malignant (approximately 30% of all tumors)
- grade III and IV are high-grade malignant (approximately 70%)
It is now more common to use a 3-point scale (French) where grade 1 is the least aggressive.