A<unk>  is a congenital, benign irregularity on the skin which is present at birth or appears shortly after birth—usually in the first month. They can occur anywhere on the skin.<unk> s are caused by overgrowth of blood vessels, melanocytes, smooth muscle, fat, fibroblasts, or keratinocytes. Dermatologists divide<unk> s into two types: pigmented<unk> s and vascular<unk> s. Pigmented<unk> s caused by excess skin pigment cells include: moles, café au lait spots, and Mongolian spots. Vascular<unk> s, also called red<unk> s, are caused by increased blood vessels and include macular stains (salmon patches), hemangiomas, and port-wine stains. A little over 1 in 10 babies have a vascular<unk>  present by age 1. Several<unk>  types are part of the group of skin lesions known as nevi or naevi, which is Latin for<unk> s".<unk> s occur as a result of a localized imbalance in factors controlling the development and migration of skin cells. In addition, it is known that vascular<unk> s are not hereditary.
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