Birthmarks with serious medical significance: nevocullular nevi, sebaceous nevi, and multiple café au lait spots.

Birthmarks of potential medical significance were identified among 4,641 newborn infants: 1.1% had a nevocellular nevus and 0.3% had a sebaceous nevus; 1.8% of black infants, but no white infants, had three or more café au lait spots. The large nevocellular nevus is considered premalignant, but the significance of the small nevocellular nevus has not been established. The sebaceous nevus fades after birth but undergoes hyperplasia at puberty. Multiple café au lait spots occur less commonly in white than in black infants, and are therefore of greater concern as possibly an early sign of neurofibromatosis.