Effective photodynamic therapy of actinic keratoses and Bowen’s disease using microneedle perforation

Funding sources: none. Conflicts of interest: none declared. MADAM, Photodynamic therapy (PDT) with 5‐aminolaevulinic acid (ALA) or its methyl ester [methyl‐5‐aminolaevulinate (MAL)] is a well‐established first‐line therapy for actinic keratoses (AKs) and Bowen’s disease.1 The thickened horny layer of skin observed in most of these diseases is known to inhibit the penetration of sufficient amounts of the photosensitizers into the atypical cells.2, 3 To overcome this obstacle, many dermatologists remove the superficial scales and crusts by gentle curettage before applying ALA or MAL.4 Here we report on three patients with keratotic AKs and Bowen’s disease on the face who did not respond to PDT with prior curettage, but show complete resolution after prior perforation with a commercially available microneedle stamp. The clinical data of the patients are shown in Table 1. All diagnoses were confirmed by histological examination. All patients were initially treated by conventional PDT, with gentle curettage of the lesions and subsequent application of the nanoemulsion‐based formulation BF‐200 ALA (10% ALA‐hydrochloride). After 3 h under plaster occlusion, protoporphyrin IX fluorescence was checked by a digital fluorescence imaging system (DyaDerm; Biocam GmbH, Regensburg, Germany), and the lesions were irradiated with a broad‐spectrum device (total dose 240 J cm−2). The treatment was carried out every other week and was stopped after five treatment courses due to the lack of significant improvement.