This is an observational longitudinal study, prospective, multicenter, performed in metropolitan France, on a representative sample of dermatologists.

Data will be collected by physicians during 2 or 3 visits (according to their usual practice), from the patient file, questioning and clinical examination performed during these visits.

Data about the patient's perception (satisfaction, perception of local skin reactions, quality of life) will be collected directly by the patient using self-administered questionnaires at inclusion visit, day 7 and 2 months later.

Actinic keratosis (AKs) are common skin diseases affecting areas previously overexposed to the sun (in particular face, nape of the neck, hands). They affect mainly elderly people (mean age: 74 years old, with 97% who are over 50 years old) and preferably men (60%). In Europe, prevalence of AK in the adult population over 40 years is estimated to be between 6% and 25%.

Subjects at risk are light-skinned people (phototype I and II according to Fitzpatrick scale) with high cumulative sun exposure or phototherapy. Over 80% of patients have a light phototype and 37% of patients with AK have an outside professional activity.

Diagnosis of AK is usually clinical, during skin examination which is recommended for any physician's visit. There are often multiple lesions, some of which, in the absence of effective treatment, can progress to squamous cell carcinoma (0.025% to 20% per year/lesion).

Although the evolution rate of AKs to carcinoma remains low and disappearance or sole persistence of the lesion is possible, their evolution is unpredictable, and it is therefore recommended to monitor and treat the AKs.

Treatment options include cryotherapy, topical treatments, photodynamic therapy, vaporization of lesions by CO2 laser or electrocoagulation and curretage.

When there are few AK lesions, which are localized and with superficial forms, cryotherapy is the reference treatment (it is widely used by dermatologists, as it is simple, fast and does not require special equipment), whereas topical treatment (5-FU, imiquimod, diclofenac) is recommended in case of multiple keratosis or lesions on a larger area of the skin. The disadvantage of cryotherapy and photodynamic therapy is that these techniques can be painful and lead to depigmentation or scarring. Topical treatments which are available (imiquimod, 5-FU, diclofenac) may induce severe inflammatory reactions sometimes responsible for premature termination and thus ineffective.

Combined with their length (4 to 16 weeks), the complexity of current topical regimens would be the cause of poor compliance.

So, all dermatologists agree with the need to shorten duration of treatment and reduce the number of applications. Ingenol mebutate gel (Picato®), used in very short 2-3 days cycle, with one application per day, meets this need.

Development of ingenol mebutate gel included 4 pivotal phase III trials, evaluating its efficacy and safety. The results of these studies have established satisfactory efficacy and safety for Picato® with, on one hand, proven efficacy after two months for face, scalp, trunk and extremities and, on the other hand, transient local skin reactions (erythema, flaking/scaling, crusting,swelling,...), which appear early, peak in intensity after the end of treatment (day 3 or day 4) and disappear without sequelae within 2-4 weeks after application of the gel. At day 57, mean patient global satisfaction scores, either assessed with TSQM or Skindex-16, were statistically higher in the ingenol mebutate gel group than in the vehicle group. In a long term follow up study, ingenol mebutate produced clinically relevant sustained clearance and long-term lesion reduction.

These characteristics are a potentially important advantage for treatment compliance as well as for patient comfort.

Inclusion Criteria:

• Patient at least 18 years old, seen by the dermatologist during a consultation, whether actinic keratosis is the reason for consultation or not.
• Patient with AK lesions and for whom the dermatologist decided to initiate a treatment with Picato®* 150 or Picato®* 500
• Patient informed and accepting the automatic processing of medical data * To respect the physicians' independence, this study is conducted among patients for whom the decision of therapeutic care is not related to their inclusion.

Exclusion Criteria:

• Patient with a contraindication to treatment with Picato®.
• Patient unable to read and/or to understand a self-administered questionnaire.
• Patient already included in the study.
• Patient participating or having participated in the previous month in a clinical trial in dermatology.

Adult patients diagnosed with actinic keratosis planned to receive treatment with ingenol mebutate at the discretion of the dermatologist