Congenital nevi

Most giant nevi are brown in color, and have an increased tendency for hair growth. The texture of the skin can be smooth or leathery and the sweat glands do not form properly. Many nevi have tumours just below the skin that give the nevus a lumpy or folded appearance. Aside from the cosmetic issues, people with giant nevi have an increased risk of developing skin cancer. Also, these same nevus cells that appear on the skin can form in the central nervous system. This condition, known as neurocutaneous melanosis, has very limited treatment and no known cure. It causes neurological problems, such as hydrocephalus (water on the brain), developmental delays, and seizures. It is potentially fatal, often within the first few years of life, and can strike anyone with a nevus.