A patient had multiple congenital giant nevocellular nevi all of which had halos but none of which regressed. This unusual phenomenon was studied histochemically and ultrastructurally in an attempt to compare this process with ordinary halo nevi and other known leukodermatous disorders. Histochemical studies demonstrated a decrease in melanin and tyrosinase activity in the area of the halo. Although the relative frequency of clear cells in the halo remained normal, electron microscopy revealed an increased density of Langerhans cells in the hypochromic zone and a variable deficit in the number of melanocytes. Ultrastructurally these melanocytes were markedly deficient in melanized melanosomes. These results suggest that either we may be dealing with an unusual form of leukoderma acquisitum centrifugum or a variant of one of the other congenital leukodermatous diseases.
Berger RS, Voorhees JJ. Multiple Congenital Giant Nevocellular Nevi With HalosA Clinical and Electron Microscopic Study. Arch Dermatol. 1971;104(5):515-521. doi:10.1001/archderm.1971.04000230057009