Which of the following is NOT a common skin characteristic of infants?

Infants' skin characteristics are quite distinct and can include several unique features that are typical during their early development. Acne, while it can occur in infants, is not considered a characteristic that is commonly observed across the majority of infants. It may result from hormonal changes or maternal hormones and typically resolves on its own, but it's not a universal trait associated with infancy like the other options listed.

Mongolian spots, vernix caseosa, and lanugo are all common skin features seen in many newborns. Mongolian spots are pigmented birthmarks that are often seen on the lower back and buttocks. Vernix caseosa is the white, cheese-like substance that covers the skin of newborns, providing protection in utero. Lanugo refers to the fine, soft hair that covers the body of fetuses, which is usually shed before birth but may still be present at birth in some infants.

Understanding these common characteristics helps in differentiating normal variations in infant skin from conditions that might require more attention or intervention.