Albino people lack the enzyme needed to convert tyrosine to melanin. The enzyme is called tyrosinase. Freckles are caused by clustering of melanocytes. Tattoos or anything that stays and doesn't get renewed along with the topmost layer of skin must be in the dermis. So a tattoo involves putting pigment into the dermis.
Moles are partly or all in the dermis.
A condition called vitilago believed to be an autoimmune disease, produces blotches of white skin among regions of normally pigmented skin. Since differentiation is slower, there are more layers of all the stages of skin development, and therefore there is a raised bump above the normal level of the skin surface. See the diagram scanned in to our web page. If you do, you could get scar tissue which on your foot could be even more of a problem than a wart. Skin cancer A. Basal cell carcinoma 1.