Periungual hyperpigmentation in newborns.

Hyperpigmentation of the distal phalanx of both hands and feet is usually a prominent feature of dark-skinned newborns, but recently it has been described also in fair-skinned ones as a coincidental finding and classified as a transient benign disorder of infancy. We report our experience, having observed a group of at-term newborns and a group of premature newborns. The group of premature newborns did not show any hyperpigmentation. On the contrary, 7 out of 40 fair-skinned at-term newborns had hyperpigmentation in the distal phalanx of the fingers which was not related to any dermatologic disorder and started to fade away after 2 years of age, i.e., longer than previously reported. The reason why some fair-skinned newborns display this hyperpigmentation is not known. Although we can speculate that it can be reactive to maternal pigment hormones, its persistence is not completely in agreement with this possibility.