Multimodal ultrasound for preoperative evaluation of dermatofibrosarcoma protuberans: a series of 40 cases

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a rare, low to intermediate-grade sarcoma, which needs imaging examination. Small series of ultrasound findings in DFSP have been published; however, the usefulness of elastography and contrast-enhanced ultrasound (CEUS) in DFSP has not been studied. We aim to study multimodal ultrasound findings and report the correlation between imagings and tiny extension in DFSP for preoperative evaluation. METHODS: Two-D ultrasound, 3-D color ultrasound, elastography, and CEUS findings were retrospectively evaluated. Forty histopathologically confirmed DFSPs were studied. RESULTS: On 2-D ultrasound, 26(65%) appeared as mostly hypoechoic lesions with occasional hyperechoic dots within the tumor matrix and lobulated lateral borders. Eight (20%) lesions were multilayered. Ninety-five percent of lesions showed increased vascularity. On 3-D ultrasound, DFSPs showed branch-shaped, striped, and wrapped color patterns. Power Doppler showed mainly artery of a moderate arterial peak systolic blood flow and low resistance index. DFSP is hard on elastography. On CEUS, DFSPs showed a long peak time, low peak and a small amount of perfusion around the tumor, 73.7% (14/19) of lesions showed a heterogeneous contrast enhancement and 89.5% (17/19) of lesions showed hyper-enhancement. CEUS showed better concordance than US with histology on the maximum diameter and depth (P < 0.05). CONCLUSIONS: Multimodal ultrasound showed significant characteristics in DFSP, which would improve diagnostic accuracy. CEUS could be an effective tool to determine tiny tumor extension.