**3.1 Tape stripping**

This technique consists in applying a tape onto the skin lesions and then to pull it off. By repeating this procedure a number times, which can be repeated using the same piece of tape, part of the SC is removed, reducing it uniformly by about 30%. This procedure is safe, since it is minimally invasive, and involves a low cost to be implemented; as a further advantage, it does not interfere with the intercellular lipids [12–14].

Tape stripping is one of the methods indicated to be applied before PDT; it can be used on patient's lips and also for the preparation of large areas. The recommendation is to choose tapes with strong adhesive properties. According to Christensen *et al*., each area can be stripped 2–4 times [15]. Some studies reported that removing SC by tape stripping significantly increases the PpIX fluorescence in the tissue but does not change the incubation time required for an effective photosensitizer production [16–18].
