Background  Photodynamic therapy (PDT) with methyl aminolaevulinate (MAL) is effective for thin actinic keratoses (AKs) in field-cancerized skin. Ablative fractional laser resurfacing (AFXL) creates vertical channels that facilitate MAL uptake and may improve PDT efficacy.

Objectives  To evaluate efficacy and safety of AFXL-assisted PDT (AFXL-PDT) compared with conventional PDT in field-directed treatment of AK.

Methods  Fifteen patients with a total of 212 AKs (severity grade I–III) in field-cancerized skin of the face and scalp were randomized to one treatment with PDT and one treatment with AFXL-PDT in two symmetrical areas. Following curettage of both treatment areas, AFXL was applied to one area using 10 mJ per pulse, 0·12 mm spot, 5% density, single pulse (UltraPulse®, DeepFx handpiece; Lumenis Inc., Santa Clara, CA, U.S.A.). MAL cream was then applied under occlusion for 3 h and illuminated with red light-emitting diode light at 37 J cm−2. Fluorescence photography quantified protoporphyrin IX (PpIX) before and after illumination.

Results  At 3-month follow-up, AFXL-PDT was significantly more effective than PDT for all AK grades. Complete lesion response of grade II–III AK was 88% after AFXL-PDT compared with 59% after PDT (= 0·02). In grade I AK, 100% of lesions cleared after AFXL-PDT compared with 80% after PDT (= 0·04). AFXL-PDT-treated skin responded with significantly fewer new AK lesions (AFXL-PDT = 3, PDT = 11; = 0·04) and more improved photoageing (moderate vs. minor improvement, = 0·007) than PDT-treated skin. Pain scores during illumination (6·5 vs. 5·4; = 0·02), erythema and crusting were more intense, and long-term pigmentary changes more frequent from AFXL-PDT than PDT (= not significant). PpIX fluorescence was higher in AFXL-pretreated skin [7528 vs. 12 816 arbitrary units (AU); = 0·003] and photobleached to equal intensities after illumination (AFXL-PDT 595 AU, PDT 454 AU; = 0·59).

Conclusions  AFXL-PDT is more effective than conventional PDT for treatment of AK in field-cancerized skin.