[Actinic keratosis: diagnostic difficulties and misinterpretation].

The diagnosis of actinic keratosis (AK) is seemingly easy, but errors by excess or default are multiple and frequent, even if they generally do not entail short-term harmful consequences. A review of possible errors and simple rules allowing to reduce them is presented here. From a practical point of view, the main risk is to misinterpret an invasive carcinoma as an AK, and to treat it as an AK, and over all a lentigo maligna. However, the misappreciation of the nosology of AK also exposes to frequent erroneous interpretations that are potentially harmful to the patients.