Similar epidermal changes in hyperkeratotic scabies of humans and pigs.

We compared some morphological and biochemical aspects of the epidermal changes occurring in hyperkeratotic scabies in humans and domestic pigs. Clinically and histologically, pig skin alterations look very similar to those observed in humans, i.e., brittle hyperkeratosis with parakeratotic crusting and thickening of the epidermis. Parakeratosis seems to correspond to previous passage of scabies mites through the incompletely differentiated layers of the epidermis. Indeed, by serial sectioning we observed beneath the stratum corneum cellular lysis some distance ahead of the mouth parts of the parasites. Epidermal cells surrounding this initial epidermolytic focus finally underwent disturbed terminal differentiation and appeared as parakeratotic cells. In pigs we observed intraepithelial microabscesses, but we rarely observed these in our human subjects.