LINEAR AND WHORLED NEVOID HYPERMELANOSIS

A case of hyperpigmentation distributed in streaks and whorls was rece ntly delineated and separated from a confusing number of pigmentary di sorders. A 13-year-old boy had hyperpigmented, reticulate spots on his trunk and neck in a linear and whorled distribution following the lin es of Blaschko. Onset was at age 1 year. Histologically, the spots sho wed increased melanin in the basal layer of the epidermis, but no incr ease in melanocytes, incontinence of pigment, or melanophages were see n in the dermis. The karyotype was 46,XY and there was no evidence of chromosomal mosaicism or chimerism. This entity represents a disorder separated recently from other pigmentary alterations that follow Blasc hko lines, such as Bloch-Sulzberger incontinentia pigmenti, hypomelano sis of Ito, early systematized epidermal nevus, and chimerism.