Halo scalp ring: a form of localized scalp injury associated with caput succedaneum.

Caput succedaneum is a common birth injury attributed to cervical, uterine, or vaginal pressure on the fetal presenting part. It usually consists of diffuse soft tissue swelling and bruising, which resolve in a few days without sequelae. We have seen two patients who had an unusual alopecic "halo" ring on the scalp associated with a caput succedaneum.