Ten skin biopsies from patients with psoriasis and pityriasis lichenoid chronica, five form eactr case, were studied in the present work,. Control skin was obtained at sura?ry. All specimens were prepared for paraffin sections for routine histological exam­ination. and immunoperoxidase stain­ing to investigate the pattern c: dioiii-butron of Langerhans cells (Lcs) in normal and involved skin with psoria­sis and pityriasis lichenoid chronica,
human- ski*a in- Urnnunope-roxictase stained sections, revealed regular suprabasal distribution of Langerhans cells in the epidermis.
In haematoxylin and eosin stained sections of psoriatic plaques, there was hyperkeratinization, hypopigmen-
tation and dermal mononuclear cell infiltration. Immunoparoxidase stained sections of psoriatic cases showed uneven epidermal distribution of Langerhans ceils. Some epidermal ar­eas were devoid of LCs, others showed few scattered cells, while an­other areas snowed large number of clumped interdigitated LCs. In these cases imrnurraperaxidiase positive cells were also detected in ilfe upper pajrt of the dermis and in dermal papil­lae.
In the present study, sections from cases with pityriasis lichenoid chronica showed hypopigmentation together with dermal mononuclear cell infiltration. Sections of these cases showed also large number of immu­noperoxidase positive LCs in the epi­dermis and among the cellular inflammatory.