[Light-microscopic study of classified virus warts (HPV-1 and HPV-4) (author's transl)].

Histological investigations of verrucae vulgares of the hand and of plantar warts show striking differences between HPV-1-induced warts and those caused by the virus type HPV-4. In warts caused by HPV-1 massive vacuolization and disturbance of epidermal cell differentiation through the entire thickness of the epidermis is predominant whereas in HPV-4 stimulated warts cell differentiation is impaired to a much lesser degree. Despite the presence of inclusions and of vacuolized cells a thick stratum granulosum and a compact horny layer are formed in the latter type.