Asymptomatic blisters on psoriatic plaques are an uncommon adverse effect of TL-01 (UVB narrow-band 312 nm) phototherapy.We report 7 new cases aiming to clarify the pathogenesis.Blisters were biopsied at different times after onset. Blood porphyrins and antibodies to nuclear antigens and the cell surface of keratinocytes were investigated.We observed 7 asymptomatic blistering eruptions strictly limited to recovering psoriatic plaques. Biopsies taken within 24 h showed junctional detachment and apoptotic necrosis of basal keratinocytes. After 48 and 72 h, the blisters were intraepithelial, due to basal cell regeneration, and were no longer evident at 96 and 120 h. Dermal inflammation was always mild. Direct immunofluorescence tests as well as stainings for p53 protein did not show substantial changes. Blood investigations were negative.TL-01 blisters are caused by the quick reduction of acanthosis and desquamation before defensive mechanisms, i.e. the increase in the thickness of the stratum corneum and pigmentation, develop. However, the pathogenetic mechanisms of apoptosis of keratinocytes remain unknown.

作者：P G, Calzavara-Pinton；C, Zane；E, Candiago；F, Facchetti

来源：Dermatology (Basel, Switzerland) 2000 年 200卷 2期