Blaschko's lines refers to lines of:
Melanocyte migration
Ectodermal cell migration
Mesodermal cell migration
Endodermal cell migration
Blaschko's lines are characteristic of mosaic conditions of the epidermis and probably represent the routes of ectodermal cell migration from the neural crest. Ref: Rook's textbook of dermatology, 8th edition, Pg 18.4.