Integrating contrast-enhanced ultrasound to optimize margin delineation in Mohs micrographic surgery for primary dermatofibrosarcoma protuberans: a retrospective cohort study

Introduction Dermatofibrosarcoma protuberans (DFSP) is characterized by infiltrative “tentacle-like” extensions, making accurate preoperative margin delineation challenging. While high-frequency ultrasound (HFUS) visualizes subclinical spread, its ability to fully capture tumor extent remains limited. Contrast-enhanced ultrasound (CEUS), by depicting microvascular perfusion, may improve delineation, but its clinical impact on Mohs micrographic surgery (MMS) remains unclear. Methods This retrospective cohort study included 220 primary DFSP patients treated with MMS. Preoperative margin delineation utilized HFUS-only or HFUS+CEUS. The primary outcome was extra peripheral Mohs stages. Secondary outcomes included extra deep and total stages, margin positivity, and other surgical characteristics. Multivariable Poisson regression with LASSO-based variable selection was used, alongside cohort-restriction, covariate-specification, and propensity score–matched (PSM) analyses. Risk-stratified and subgroup analyses explored effect heterogeneity. Results HFUS+CEUS was associated with fewer extra peripheral Mohs stages than HFUS-only (adjusted incidence rate ratio [aIRR], 0.310; P = 0.049). Peripheral margin positivity was reduced from 17.4% to 5.1% (P = 0.020). These findings were consistent across sensitivity analyses and in the PSM cohort (aIRR, 0.309; P = 0.033). The relative effect was most pronounced in the high-risk stratum (IRR, 0.124; P = 0.041), although interaction testing was not statistically significant (P = 0.077). No significant differences were observed in deep or total stages, likely due to ultrasound depth limitations. Conclusions Integrating CEUS with HFUS enhances the precision of preoperative margin delineation for DFSP, reducing extra peripheral Mohs stages. This multimodal imaging strategy represents a valuable, tissue-sparing refinement to the preoperative workflow of MMS, particularly for patients with higher baseline risk.