Unusual clinical presentation of regression in a congenital melanocytic nevus

Spontaneous Involution of Congenital Melanocytic Nevus With Halo Phenomenon

Congenital melanocytic nevus (CMN) is a neural crest-derived hamartoma, which appear at or soon after birth. CMN has a dynamic course and may show variable changes over time, including spontaneous involution. Spontaneous involution of CMN is a rare phenomenon and is often reported in association with halo phenomenon or vitiligo. The mechanism of halo phenomenon is yet to be investigated but is suggested to be a destruction of melanocytes by immune responses of cytotoxic T cells or IgM autoantibodies. Here, the authors report an interesting case of spontaneously regressed medium-sized CMN with halo phenomenon and without vitiligo, which provides evidence that cytotoxic T cells account for the halo formation and pigmentary regression of CMN.

Hypomelanotic Conditions of the Newborn and Infant

Depigmented nevi, pityriasis alba, and postinflammatory hypopigmentation are the most frequent hypomelanotic conditions in newborns and infants. These, and examples of less frequent hypopigmentations are briefly discussed in this article. A new classification for depigmented nevi is also proposed.