The most common skin abnormalities include:
* Facial angiofibromas ("adenoma sebaceum"): A rash of reddish spots or bumps, which appear on the nose and cheeks in a butterfly distribution.
* Periungual fibromas: Also known as Koenen's tumors, these are small fleshy tumors that grow around and under the toenails or fingernails.
* Hypomelanic macules ("ash leaf spots"): White or lighter patches of skin that may appear anywhere on the body and are caused by a lack of melanin. These are usually the only visible sign of tuberous sclerosis at birth.
* Shagreen patches: Areas of thick leathery skin that are dimpled like an orange peel, usually found on the lower back or nape of the neck.