A Novel Non-Invasive Scoring System for Differentiating DFSP and Keloids.

BACKGROUND: Differentiating dermatofibrosarcoma protuberans (DFSP) from keloids presents significant clinical challenges, particularly when skin biopsies are contraindicated. This study introduces a novel, non-invasive diagnostic method leveraging the Japan Scar Workshop Scar Scale (JSS) combined with the cosine of the angle (cosθ) to distinguish between these conditions. METHODS: In this case-control study, 43 cases were retrospectively analyzed using the new evaluation method, JSS × cosθ, designed specifically for this differential diagnosis. This method applies JSS in conjunction with cosθ to assess lesion characteristics non-invasively. RESULTS: The JSS × cosθ scores effectively differentiated between DFSP and keloids. Scores ≥16 were indicative of keloids, whereas scores <16 suggested DFSP, with these findings achieving statistical significance ( p  < 0.001). CONCLUSION: The JSS × cosθ scoring system provides a reliable and safe diagnostic tool for distinguishing DFSP from keloids, particularly in cases where biopsy is avoided due to the risk that stimulation of the reticular dermis may lead to the development, enlargement, or worsening of keloids. This method promises to significantly impact the specific management of DFSP and keloids.