Two cases of localized epidermolytic hyperkeratosis, investigated by electron microscopy, show the dermis and basal cell region to be normal. The "halos" in routine paraffin sections proved to be large areas of perinuclear endoplasmic recticulum which with other morphologic evidence represent signs of increased metabolic activity. The cause of hyperkeratosis in epidermolytic hyperkeratosis is increased epidermal cell turnover and increased speed of migration of epidermal cells towards the horny layer. A concept as to the role of the keratinosome in the formation of the horny layer is presented.
WILGRAM GF, CAULFIELD JB. An Electron Microscopic Study of Epidermolytic HyperkeratosisWith a Special Note on the Keratinosome as the "Fourth" Structural Factor in the Formation of the Horny Layer. Arch Dermatol. 1966;94(2):127–143. doi:10.1001/archderm.1966.01600260019002