Unraveling the patterns of subclinical pheomelanin-enriched facial hyperpigmentation:: Effect of depigmenting agents

Background: During photoaging, the density of melanin chromatophores is heterogeneous in the epidermis. Aims: To define the patterns of pheomelanin-enriched melanotic hypermelanosis of the face in phototype II subjects and to assess the effect of depigmenting agents. Azelaic acid and glycolic acid were tested as well as a soy extract, reported to reduce pigmentation through interaction with the protease-activated receptor 2 (PAR-2) of keratinocytes. Method: Evaluations were made by image analysis of high magnification pictures obtained by a video camera equipped with an internal ultraviolet-emitting unit (Visioscan(R)). Results: Three patterns of subclinical facial hypermelanosis were recognized including the spotty perifollicular type, the accretive globular type and the elongated type of the sunny side of wrinkles. Azelaic acid and the soy extract led to significant skin lightening after a 3-week treatment. By contrast, glycolic acid showed an inconsistent effect. Conclusion: Sensitive fluorescence video recording combined with image analysis represents an advance in the noninvasive assessment of the mottled subclinical skin pigmentation. The depigmenting effect observed with the soy extract indicates that the inhibition of PAR-2 may be a novel way to approach certain pigmentary disorders of the skin. Copyright (C) 2000 S. Karger AG, Basel.