The delineation of tumor borders, particularly in anatomically difficult sites such as the face, is a frequent problem in clinical routine. Multiple surgical procedures may be necessary for complete tumor removal. FDAP is a very effective method to detect neoplastic tissue in pretreated and sunlight-damaged skin and to demarcate clinically ill-defined tumor tissue. Therefore, FDAP can be recommended as a useful and easy technique to visualize and detect the size and extension of a certain tumor preoperatively. Similarly to urology, where FDAP is already used in various urological clinics as a routine technique for the detection of bladder cancers, this useful tool is now introduced into dermatology. FDAP should not be seen as an equivalent to histological examination that defines the malignancy or classification of skin tumors. The main advantage of FDAP is the identification of the borders between tumor and normal skin, thus improving the planning of further therapeutic strategies.