title: Histogenesis of keratoacanthoma: histochemical and immunohistochemical study.
abstract: OBJECTIVE
  Keratoacanthoma (KA), a keratinocytic neoplasm, is associated with sun exposure and is often found in the head and neck area, including the lip. KA is thought to arise from hair follicle cells, but its origin is largely unknown. Keratins (Ks) and histochemical stains are of great value to characterize and identify normal and neoplastic cells. The objective of this study is to analyze a panel of Ks and periodic acid-Schiff (PAS) staining on KA.
  
  
  METHODS
  Using KA biopsies from the lips and normal skin samples, we performed immunohistochemical and histochemical profiling to determine which biomarkers are conserved between tumors and normal tissues.
  
  
  RESULTS
  The normal hair follicle has multiple well-defined compartments. The outer root sheath (ORS) cells presented K6 and K14 and were also PAS positive. In addition, the infundibulum cells showed positive labeling to K10. Hair cortex keratin was observed in the cortical and precortical cells. Interestingly, KA tumor cells were positive for PAS, K6, K10, and K14 but not to hair cortex keratin. Lip and skin epithelium were negative for PAS and K6.
  
  
  CONCLUSIONS
  Our results indicate that KA of the lip is derived from ORS cells, particularly those cells associated with the upper ORS.
authors.affiliation: Department of Oral Pathology, School of Dentistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil 90035.
authors.forename: Vivian Petersen
authors.initials: VP
authors.lastname: Wagner
authors.affiliation: Department of Oral Pathology, School of Dentistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil 90035.
authors.forename: Manoela Domingues
authors.initials: MD
authors.lastname: Martins
authors.affiliation: Department of Oral Pathology, School of Dentistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil 90035.
authors.forename: Caroline Siviero
authors.initials: CS
authors.lastname: Dillenburg
authors.affiliation: Department of Pathology, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil 90035.
authors.forename: Luise
authors.initials: L
authors.lastname: Meurer
authors.affiliation: Laboratory of Epithelial Biology, Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA 48109.
authors.forename: Rogerio Moraes
authors.initials: RM
authors.lastname: Castilho
authors.affiliation: Laboratory of Epithelial Biology, Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA 48109. Electronic address: Csquariz@umich.edu.
authors.forename: Cristiane Helena
authors.initials: CH
authors.lastname: Squarize
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D005260:Female; D006201:Hair Diseases / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D007636:Keratoacanthoma / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D010503:Periodic Acid-Schiff Reaction
chemical_list: D014408:Biomarkers, Tumor