A very common, harmless skin condition, also known as erythema neonatorum or toxic erythema, that affects newborn infants. A blotchy rash, in which raised white or yellow lumps are surrounded by illdefined red areas of inflammation, forms, mainly affecting the face, chest, arms, and thighs. The cause of neonatal urticaria is unknown. The rash usually clears up without treatment.... urticaria, neonatal