Grading of subcutaneous soft tissue tumors by means of their relationship with the superficial fascia on MR imaging.

OBJECTIVE: To assess the diagnostic value of the relationship between subcutaneous tumors and the superficial fascia in the characterization of soft-tissue masses.
DESIGN: MR studies of 64 soft tissue masses located in the subcutaneous space were reviewed. We established five grades of relationship between tumors and superficial fascia and analyzed the probability of the lesions in each group being malignant. Group 1 tumors did not contact the fascia; group 2 lesions contacted it slightly, with acute angles between the tumor and the fascia; group 3 lesions had wider contact with larger acute or right angles; group 4 tumors had even wider contact with obtuse angles with the fascia; and group 5 was composed of lesions that crossed the superficial fascia.
RESULTS: The probability of a subcutaneous lesion that crosses the superficial fascia being malignant was 6.88 times greater than for lesions that did not cross the fascia. For lesions forming obtuse angles with the fascia the probability of malignancy was 6.3 times greater than that of tumors that did not present this sign. All histologically verified fascial infiltrations occurred in malignant lesions of groups 4 and 5.
CONCLUSIONS: Malignant tumors of the subcutaneous compartment have a higher tendency to develop a close relationship with the fascia than benign lesions. Obtuse angles between superficial fascia and a subcutaneous mass or a lesion crossing the fascia strongly suggest malignancy.