title: Blisters on psoriatic lesions treated with TL-01 lamps.
abstract: BACKGROUND
  Asymptomatic blisters on psoriatic plaques are an uncommon adverse effect of TL-01 (UVB narrow-band 312 nm) phototherapy.
  
  
  OBJECTIVE
  We report 7 new cases aiming to clarify the pathogenesis.
  
  
  METHODS
  Blisters were biopsied at different times after onset. Blood porphyrins and antibodies to nuclear antigens and the cell surface of keratinocytes were investigated.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Dermatology, Spedali Civili, Brescia University School of Medicine, Brescia, Italy. calzavar@bshosp.osp.unibs.it
authors.forename: P G
authors.initials: PG
authors.lastname: Calzavara-Pinton
authors.forename: C
authors.initials: C
authors.lastname: Zane
authors.forename: E
authors.initials: E
authors.lastname: Candiago
authors.forename: F
authors.initials: F
authors.lastname: Facchetti
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017209:Apoptosis; D001323:Autoantibodies / Q000032:analysis; D001768:Blister / Q000209:etiology* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000276:immunology / Q000473:pathology; D019394:Ki-67 Antigen / Q000032:analysis; D008297:Male; D008875:Middle Aged; D011166:Porphyrins / Q000097:blood; D011446:Prospective Studies; D011565:Psoriasis / Q000097:blood / Q000276:immunology / Q000473:pathology / Q000532:radiotherapy*; D012867:Skin / Q000473:pathology; D014467:Ultraviolet Therapy / Q000009:adverse effects*
chemical_list: D001323:Autoantibodies; D019394:Ki-67 Antigen; D011166:Porphyrins