title: Inducible nitric oxide synthase in pityriasis lichenoides lesions.
abstract: BACKGROUND
  Pityriasis lichenoides (PL) is an inflammatory skin disease of unknown etiology. Nitric oxide (NO) has emerged as an important mediator of many physiological functions. The importance of NO-mediated signaling in skin diseases has been reported by several studies.
  
  
  METHODS
  A review of clinical records and histopathological slides of 34 patients diagnosed with PL was performed. Three different groups of skin biopsies including PL chronica (24 patients), PL et varioliformis acuta (10 patients) and 15 normal skin samples were subjected to the immunohistochemistry technique for inducible nitric oxide synthase (iNOS) detection.
  
  
  RESULTS
  Normal skin group exhibited a few number of iNOS-positive cells in the dermis and rare positive cells in the upper epidermis, unlike abundant epidermal and dermal iNOS expression observed in both PL groups.
  
  
  CONCLUSIONS
  According to our results, we hypothesize that NO produced by iNOS could participate in PL pathogenesis. Abnormal and persistent responses to unknown antigens, probably a pathogen, associated with NO immunoregulatory functions could contribute to the relapsing course observed in PL. NO anti-apoptotic effect on T-cell lymphocytes could play a role on maintenance of reactive T cells, leading to a T-cell lymphoid dyscrasia.
authors.affiliation: Department of Pathology, Santa Catarina Federal University, Florianópolis, Brazil. zazagdg@hotmail.com
authors.forename: Gabriella
authors.initials: G
authors.lastname: Di Giunta
authors.forename: Ana M Gonçalves
authors.initials: AM
authors.lastname: da Silva
authors.forename: Mirian N
authors.initials: MN
authors.lastname: Sotto
mesh_terms: D020405:Dermis / Q000201:enzymology* / Q000473:pathology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007249:Inflammation / Q000201:enzymology / Q000473:pathology; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis*; D017514:Pityriasis Lichenoides / Q000201:enzymology* / Q000473:pathology; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000201:enzymology / Q000473:pathology
chemical_list: D009569:Nitric Oxide; C496319:NOS2 protein, human; D052247:Nitric Oxide Synthase Type II