The objective of this study is to translate the "AKQoL"-questionnaire which measures the quality of life of patients with actinic keratosis into German and to validate it for the Swiss population.

By using the technique of cognitive interviewing the investigators are focussing on the patients' understanding of the questions. The first session of cognitive interviews will show, where there is need for improvement in terms of misinterpreted phrases or vaguely worded questions. The goal is to rephrase the questions according to the feedback of the patients. The revised version will then be presented to a new population.

Actinic keratosis is a UV-induced skin disease, which presents as a reddish, squamous and sometimes itchy lesion. Actinic keratosis seems to have a negative impact on patients' quality of life. Esmann et al. elaborated on patients with actinic keratosis from Zealand, Denmark a questionnaire which measures the quality of life.

The objective of this study is to translate this questionnaire into German and to validate it for the Swiss population. This questionnaire might become part of a planned national register for data collection of patients with AK.

The investigators will assess the content validity of the questionnaire by using the technique of cognitive interviewing. The investigators are going to talk 34 patients with AK from the department of Dermatology, University Hospital Zurich through the translated version. Thereby, the investigators are focusing on the patients' understanding of the questions.

The first session of cognitive interviews will show, where there is need for improvement in terms of misinterpreted phrases or vaguely worded questions. The goal is to rephrase the questions in the sense that they become more clear and are understood by different interviewee in the same way. The revised version will then be presented to a new population. The performance of cognitive interview sessions and revisions will continue until the survey will be approved by at least 80% of the respondents.

Inclusion Criteria:

• Patients with actinic keratosis of the department of Dermatology, University Hospital Zurich
• Male and Female subjects > 18 years of age
• Good understanding of written and spoken German
• Sufficient physical and mental capacity to comprehend the questions
• Written informed consent by the participant

Exclusion Criteria:

• Lack of informed consent