Introduction: Expansive masses arising from periskeletal soft tissues are a frequent challenge for the imaging specialist. Lesion diagnosis and characterization, and the assessment of benign/malignant nature are very important factors for treatment planning. We investigated MR capabilities in distinguishing benign from malignant masses and for histopathologic lesion characterization, also in the light of the latest most authoritative literature reports.
Material and methods: February 1995 to November 1997, we examined 237 patients with known space-occupying lesions arising from periskeletal soft tissues. T1- and PD/T2-weighted SE images were acquired on the most suitable planes. The findings were independently evaluated by two groups of radiologists who were asked a benignity/malignancy judgment based on specific morphological criteria and then a presumptive histopathologic characterization. The results were then compared with pathologic findings.
Results: We had high agreement rates for benignity/malignancy judgements, with only < or = 3.8% error rates. In contrast, rates were quite variable for histopathologic characterization and differed greatly by lesion type. The lesions, defined as malignant, could not be characterized histologically in approximately 18% of cases by both groups.
Discussion and conclusions: Our results, which are in substantial agreement with the recent authoritative literature, confirm MRI as an extremely reliable tool for distinguishing benign from malignant expansive masses arising from periskeletal soft tissues. On the contrary, MRI exhibits good specificity in histopathologic characterization only for the masses with such development as to permit identification of the anatomical compartment of origin, which are usually benign, as well as the masses with typical or pathognomonic tissue signal.