title: The possible role of trauma in skin tags through the release of mast cell mediators.
abstract: BACKGROUND
  Skin tags (ST) are common benign tumors of the skin but their etiopathogenesis is not well understood. STs arise in sites subjected to trauma. It was proved that mast cells are recruited to sites of skin trauma and increase their tumor necrosis factor-α (TNF-α) content.
  
  
  OBJECTIVE
  STs are linked to obesity and frictional sites, but this has not been studied at the molecular level. We hypothesized that mast cells, TNF-α and its family member, TNF-related apoptosis-inducing ligand (TRAIL) might play a role in the pathogenesis of STs as a response to trauma.
  
  
  METHODS
  A study was done on 15 patients with STs. Two STs and a snip of normal skin were obtained in each subject. We counted the mast cells after Toluidine blue staining. Enzyme-linked immunosorbant assay was used to measure TNF-α level while reverse transcriptase polymerase chain reaction was used to evaluate the level of TRAIL mRNA expression.
  
  
  RESULTS
  Mast cell count in all STs was significantly higher than that in control (P=0.0355). There was a highly significant increase in the level of TNF-α in all STs as compared to its level in controls (P<0.0001). Expression of TRAIL mRNA was significantly higher in STs as compared to its expression in controls (P<0.0001).
  
  
  CONCLUSIONS
  Our study suggests that mast cells, TNF-α and TRAIL may play a role in the pathogenesis of STs.
authors.affiliation: Dermatology Department, Faculty of Medicine, Cairo University, Egypt .
authors.forename: Omar S
authors.initials: OS
authors.lastname: El Safoury
authors.forename: Marwa M
authors.initials: MM
authors.lastname: Fawzy
authors.forename: Rania M Abdel
authors.initials: RM
authors.lastname: Hay
authors.forename: Akmal S
authors.initials: AS
authors.lastname: Hassan
authors.forename: Zeinab M
authors.initials: ZM
authors.lastname: El Maadawi
authors.forename: Laila A
authors.initials: LA
authors.lastname: Rashed