European consensus-based interdisciplinary guideline for diagnosis, treatment and prevention of actinic keratoses, epithelial UV-induced dysplasia and field cancerization on behalf of European Association of Dermato-Oncology, European Dermatology Forum, European Academy of Dermatology and Venereology and Union of Medical Specialists (Union Européenne des Médecins Spécialistes).

A collaboration of multidisciplinary experts from the European Association of Dermato-Oncology, the European Dermatology Forum, the European Academy of Dermatology and Venereology, and the European Union of Medical Specialists was formed to develop European recommendations on AK diagnosis and treatment, based on current literature and expert consensus. This guideline addresses the epidemiology, diagnostics, risk stratification and treatments in immunocompetent as well as immunosuppressed patients. Actinic keratoses (AK) are potential precursors of cutaneous squamous cell carcinoma (cSCC) and display typical histopathologic and immunohistochemical features of this malignancy in an early stage. They can develop into cSSC in situ and become invasive in a low percentage of cases. AK is the most frequent neoplasia in white populations, frequently occurring within a cancerous field induced by ultraviolet radiation. Since it cannot be predicted, which lesion will progress to cSCC and when treatment is usually recommended. The diagnosis of AK and field cancerization is made by clinical examination. Dermatoscopy, confocal microscopy, optical coherence tomography or line-field confocal-OCT can help in the differential diagnosis of AK and other skin neoplasms. A biopsy is indicated in clinically and/or dermatoscopically suspicious and/or treatment-refractory lesions. The choice of treatment depends on patients' and lesion characteristics. For single non-hyperkeratotic lesions, the treatment can be started upon patient's request with destructive treatments or topical treatments. For multiple lesions, field cancerization treatment is advised with topical treatments and photodynamic therapy. Preventive measures such as sun protection, self-examination and repeated field cancerization treatments of previously affected skin areas in high-risk patients are advised.

Pretreatment with 5-Fluorouracil Cream Enhances the Efficacy of Daylight-mediated Photodynamic Therapy for Actinic Keratosis.

The efficacy of photodynamic therapy (PDT) with methyl aminolevulinate is reduced when treating actinic keratosis (AK) on the extremities in comparison with the face and scalp. Studies indicate that PDT efficacy can be improved by combining PDT with other treatment modalities. This randomized intra-individual study investigated whether pretreatment with topical 5% 5-fluorouracil (5-FU) enhanced the treatment efficacy of daylight-mediated PDT in 24 patients with AKs on the hands. One hand of each patient was given 7 days of pretreatment with 5-FU twice daily before daylight-PDT, whereas the other hand was treated with daylight-PDT alone. At 3-month follow-up the overall lesion response rate was significantly higher for the combination of 5-FU and daylight-PDT (62.7%) than for daylight-PDT alone (51.8%) (p = 0.001). Furthermore, pain and erythema in relation to treatment were similar in the 2 groups (p = 1.0 and p = 0.2, respectively). Combination therapy is a safe and effective method to improve daylight-PDT for acral AKs.