Light and Electron Microscopic Study of Riehl's Melanosis. Possible Mode of its Pigmentary Incontinence

Four cases of Riehl's melanosis were studied with light and electron microscopes. The results obtained were as follows: Unmyelinated nerve fibers were found in both the epidermis and the dermis, and the Schwann cells enclsing the axons contained melanosomes. A peculiar pigment cell was found in the epidermis, it was thought to be a macrophage phagocytizing melanosomes from the extracellular spaces. A melanophage in contact with a keratinocyte through the gaps of the basal lamina was observed. It was suggested that all these processes might participate in pigmentary incontinence in Riehl's melanosis. At the dermo‐epidermal junction the basal lamina was multilayered. In the upper dermis a large number of melanophages were present, and in addition, amyloid islets and fibrillar masses resembling the “fibrilläre Körper” were observed.