A weighted scoring system to differentiate malignant liposarcomas from benign lipomas.

PURPOSE To construct a scoring system to differentiate malignant liposarcomas from benign lipomas by comparing their clinical and magnetic resonance imaging (MRI) features. METHODS Clinical and MRI features of 33 women and 33 men aged 17 to 83 (mean, 53) years who underwent resection of malignant liposarcomas (n=32) or benign lipomas (n=34) were reviewed. RESULTS The 5 strongest predictors of liposarcoma were male gender, larger tumour maximum dimension, deep to fascia, thick non-fatty septum or nodule, and internal cystic change. A weighted scoring system was constructed using the 5 strongest predictors as: Z score=10X1+X2+12X3+15X4+10X5, respectively. A cut-off score of 35 was used; all 32 malignant liposarcomas and 4 of 34 benign lipomas scored >35. The cut-off score of ≤35 could predict 30 of 66 lipomatous tumours as benign with a negative predictive value of 100% (p<0.0001). CONCLUSION The 5 strongest clinical and MRI features were identified to construct a scoring system to differentiate malignant from benign lipomatous tumours. Further validation in independent populations is required.