blocking, TiO is extensively used in sunscreens. The potential toxicity of TiO2 is an important public health concern as TiO 2 is classified by the International Agency for Research on Cancer (IARC) as an IARC Group 2B carcinogen. Concerning the skin, it is still debated whether TiO 2 does or not penetrate the stratum corneum, but it has been clearly demonstrated that it can deposit in the follicular orifice. 4 To date, there are no available data concerning the impact of TiO 2 cutaneous exposure on hair growth. However, the detection of TiO 2 along the hair shafts of our patient raises the question of a possible implication of TiO 2 in FFA pathogenesis via an allergic process. This hypothesis is based on the fact that lichen planus, which is a close or even the same entity as FFA, can be a consequence of metal sensitization, especially for oral lichen planus in association with dental implants containing nickel, iron or zinc. 5 Moreover, there are several reports of contact dermatitis or granulomatous reactions induced by TiO 2 upon its use in pacemakers, hip prostheses or osteosynthesis, showing that TiO 2 can be a target allergen for T-cell lymphocytes. 6 Further studies are needed to confirm this potential link.