Blashco's lines are present along the

Blaschko's Lines: a. The lines of Blaschko were delineated over 100 years ago. b. First described by Blaschko in 1901. The pattern is attributed to the lines of migration and proliferation of epidermal cells during embryogenesis (i.e., the bands of abnormal skin represent clones of cells carrying a mutation in a gene expressed in the skin).