Background  Mohs micrographic surgery is a tissue sparing surgical technique for removal of skin cancer. To optimize the cosmetic result of scars and skin grafts after surgery non invasive procedures as non-ablative fractional laser (NAFL) resurfacing are attractive.

Objective  To evaluate efficacy and safety of 1540 nm NAFL in the treatment of scars and skin grafts after Mohs micrographic surgery.

Methods  An intra-individual randomized controlled trial (RCT) with split lesion design and single blinded outcome evaluations. Patients receive four treatments at monthly interval with NAFL [StarLux-300 with Lux 1540 nm fractional handpiece (Palomar technologies)]. Primary endpoint to evaluate efficacy is a blinded on site visual and palpable Physician Global Assessment (PhGA). Adverse event and pain registration are used to evaluate safety. Patient’s global assessment (PGA) and skin reflectance measurements are secondary endpoints.

Results  The PhGA score comparing the treated to the untreated control side of 24 patients is significant different 1 (P = 0.009) and 3 (P = 0.001) months after treatment (Wilcoxon signed rank test). Patients experienced mild to moderate pain. Four days after the treatments patients reported erythema (67%), oedema (31%), crusts (22%), burning sensation (14%), purpura (9%) and vesicles (4%). No long term adverse events are reported. PGA is significant different 1 (< 0. 001) and 3 months (< 0. 001) after the last treatment. Skin reflectance do not show significant difference.

Conclusion  This study shows that nonablative 1540 nm fractional laser is a safe and effective treatment for the improvement of scars and grafts after Mohs surgery.