A Histologic Study of the Dermoepidermal Junction in Clinically “Intradermal” Nevi, Employing Serial Sections

According to prevalent opinion the natural history of cellular nevi] can be summarized as follows: In human fetal life neuroectodermally derived melanoblasts migrate through the primitive mesenchyme to the basal layer of the epidermis where they eventually become mature melanocytes (Zimmerman and Becker, Jr., 1959).For unknown reasons, some of these cells in the lower layers of the epidermis and on its undersurface proliferate in discrete areas to form aggregates that then lose their normal relationship with the adjacent keratinocytes (prickle cells) (Ebert, 1938).Such clusters of melanocytes are termed junctional nevus cells, or, simply, junctional thequest (nests).It is as yet unclear at which stage intraepidermal melanoblasts (prenevus cells?melanocytes?)become recognizable "nevus cells."During the early years of life virtually all cellular nevi are primarily composed of junctional theques (Unna, 1896) and therefore are called "junctional nevi" § (Traub and Keil, 1940;Sachs et al., 1947;and Stegmaier and Montgomery, 1953).As nevi grow older the cells comprising the junctional theques push their way into the upper cutis and finally completely lose their epidermal contact, at which time they are referred to as dermal nevus cells.In the intermediate stages of this process junctional theques are found at the dermoepidermal junction and nevus cells are seen in the dermis.Nevi showing this combination are then called "compound nevi"~(Allen, 1949).Finally, according to common teaching, in most of the cellular nevi in adults all of the junctional theque cells "drop down" (Abtropfung of Unna, 1893 and 1894) into the cutis and none remain at the dermoepidermal junction.Such nevi are referred to as "intradermal nevi."Although it is not pertinent to this paper, which deals solely with the june-