title: An immunohistochemical study of abnormal keratinocyte proliferation in molluscum contagiosum.
abstract: BACKGROUND
  Molluscum contagiosum is a common cutaneous tumour that is characterized by usually spontaneous involution and self-limited spreading in immunocompetent individuals.
  
  
  OBJECTIVE
  We aimed to investigate the apoptosis and the expression of cell-cycle proteins in molluscum contagiosum lesions.
  
  
  METHODS
  The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL)-based apoptotic index and the expression of the cell-cycle proteins Ki-67, p53, p21WAF and Bcl-2 were investigated in molluscum contagiosum lesions obtained from the trunk of 20 immunocompetent patients and in normal skin samples from the trunk of six healthy volunteers.
  
  
  RESULTS
  Whereas molluscum contagiosum lesions displayed a TUNEL-based apoptotic index similar to that of normal skin, they exhibited an increased Ki-67 index, which was confined to the basal and first suprabasal layers (P < 0.001). Compared with normal non-sun-exposed skin, molluscum contagiosum lesions also exhibited increased p53 staining in basal cells (P < 0.01), increased p21WAF in suprabasal cells (P < 0.001) and loss of Bcl-2 expression.
  
  
  CONCLUSIONS
  These results indicate that molluscum contagiosum lesions exhibit an increased proliferation rate of keratinocytes, which is likely to be partially counteracted by accumulation of p53.
authors.affiliation: Department of Dermatology, Erasme University Hospital, 808 Route de Lennik, B-1070 Brussels, Belgium. tsimonar@ulb.ac.be
authors.forename: T
authors.initials: T
authors.lastname: Simonart
authors.forename: I
authors.initials: I
authors.lastname: Fayt
authors.forename: J C
authors.initials: JC
authors.lastname: Noel
mesh_terms: D017209:Apoptosis; D002455:Cell Division; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D006801:Humans; D020287:In Situ Nick-End Labeling; D015603:Keratinocytes / Q000378:metabolism / Q000473:pathology*; D019394:Ki-67 Antigen / Q000378:metabolism; D008976:Molluscum Contagiosum / Q000378:metabolism / Q000473:pathology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D019394:Ki-67 Antigen; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53