Immunohistochemical study of the early histopathologic changes occurring in trauma-injured skin of psoriatic patients

In the present study we have investigated the early histopathologic as chan ges occurring in the Koebner reaction induced by traumatic injury in uninvo lved skin of 23 psoriatic and 7 non-psoriatic control patients. A punch bio psy of the injured area was performed after 2-3 (15 cases) or 7 days (8 cas es). As a trauma, instead of the classic sellotape stripping, needle scarif ication was used. A peculiar histological feature of the skin biopsies of 13/23 psoriatic pat ients (56%) was a keratinocyte hyperplasia leading to a "papillary" project ion into the upper dermis, just beneath the scarification. The papillary pr ojection was associated with the expression of intercellular adhesion molec ule-1 (ICAM-1) in the keratinocytes of 9/13 cases (70%) and with the presen ce of peri-papillary aggregates of CD68(+) cells in 10/13 cases. In the upp er dermis, tenascin was markedly expressed in 12/13 cases. Moreover, in one third of the cases, just beneath the scarification, there was reabsorption of the epidermal basal membrane as documented by a marked reduction of col lagen type IV and laminin content. These histopathological alterations were detected in 6/15 psoriatic patient s whose skin biopsy was taken 2-3 days after scarification, in 7/8 after 7 days, and in only 1/7 non psoriatic controls. Our results indicate that needle scarification can be a suitable method to study the early events occurring in trauma injured psoriatic skin.