MRI of superficial soft tissue masses: analysis of features useful in distinguishing between benign and malignant lesions.

AIM: To identify the MRI features of superficial soft tissue masses, that may allow differentiation between malignant and non-malignant lesions.
METHOD: A total of 136 consecutive patients referred to a supra-regional musculoskeletal oncology center over a 10-year period with the diagnosis of a superficial soft tissue mass were included in this retrospective study. Features analyzed included patient demographics, lesion size, MRI signal characteristics, margins, lobulation, hemorrhage, necrosis, fascial edema, relationship to the fascia, as well as involvement of the skin. Comparison was then made with the final histological diagnosis.
RESULTS: Of the patients reviewed, 58 were male and 78 were female, and the mean age was 49.9 years. The mean age for malignant lesions was 57.9 years, and that for non-neoplastic and benign conditions 41.9 years (p < 0.001). A significant relationship was identified between malignancy and lobulation (p < 0.01), hemorrhage (p < 0.001), fascial edema (p < 0.001), hemorrhage (p < 0.0001) and necrosis (p < 0.001). The relationship between skin thickening and skin contact and malignancy was also found to be significant. However, size was not found to be an important determining factor for malignancy, with a significant proportion of malignant superficial sarcomas measuring less than 5 cm in maximal diameter.
CONCLUSIONS: This study has shown that a significant proportion of malignant superficial sarcomas measured less than 5 cm in maximal diameter. Fascial edema, skin thickening, skin contact, hemorrhage, and necrosis were found to be highly significant factors indicative of malignancy. Lobulation and peritumoral edema were also significant MRI features.