MRI-Based Surgical Margin Assessment in Dermatofibrosarcoma Protuberans: Correlation With Pathological Extent.

The median planned lateral margin was 20 mm, whereas the median pathological margin was 16.5 mm.

The median difference (pathological - planned) was -5 mm (interquartile range -10.25 to -1 mm; range -18 to +15 mm), with planned margins significantly larger (p < 0.001).

A weak positive correlation was observed between planned and pathological margins (ρ = 0.32), but it did not reach statistical significance (p = 0.060).

Residual tumor was identified in 71% of patients undergoing additional resection after unplanned excision.