| Neoplastic cells were cuboidal to polygonal, with variable degrees of squamous differentiation and cornification toward the center of nests. |
| Several factors are involved in the pathogenesis: inheritance, increased sebum production, an abnormality of the microbial flora, cornification of the pilosebaceous duct and the production of inflammation. |
| The changes were a heightened incidence of increased cornification of the fore-stomach mucosa and basal cell proliferation at the level of the cardia. |
| Nails arise in the interior of the epidermis by the thickening and cornification of the stratum lucidum. |
