TXA decreased epidermal pigmentation associated with melasma and also reversed melasma-related dermal changes, such as vessel number and increased numbers of mast cells.

Melasma skin is characterized by impaired stratum corneum integrity and a delayed barrier recovery rate.

These cases seem to represent a continuum of Riehl melanosis. However, the principal distribution of the pigmentation is a distinguishing feature. Any consistent predisposing factors were not established, but there may be a role for subclinical injury or inflammation as possible causative factors for development of the pigmentation.

This study demonstrates that the decreased expression of VDR in AA and AU lesions is related to decreased expression of Wnt/β-catenin signals, which inhibits proliferation and differentiation of hair follicles and epidermal cells.