title: p16 expression in cutaneous squamous carcinomas with neck metastases: a potential pitfall in identifying unknown primaries of the head and neck.
abstract: BACKGROUND
  Human papillomavirus (HPV) positivity (+) has been used to identify oropharyngeal squamous carcinomas (SCCs) presenting as unknown primaries in the neck. p16 overexpression correlates with HPV+ in the oropharynx; however, the use of p16 alone as a surrogate marker of oropharyngeal HPV+ tumors has not been validated.
  
  
  METHODS
  We immunohistochemically analyzed p16 expression in surgically resected aggressive cutaneous head and neck SCC primaries and their nodal metastases from 24 patients to determine the potential overlap of p16 expression outside of the oropharynx.
  
  
  RESULTS
  Five of 24 primary tumors (20.8%) and 3 lymph node metastases (12.5%) in levels II, III, and V, and the periparotid region diffusely expressed p16. HPV (high-risk types by in situ hybridization) was negative.
  
  
  CONCLUSIONS
  p16 expression is relatively common in lymph node-positive cutaneous head and neck SCCs; thus, p16 expression as an independent biomarker and mechanism to determine the oropharyngeal source of an unknown primary is not advised.
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Beth M
authors.initials: BM
authors.lastname: Beadle
authors.forename: William N
authors.initials: WN
authors.lastname: William
authors.forename: Michael S
authors.initials: MS
authors.lastname: McLemore
authors.forename: Erich M
authors.initials: EM
authors.lastname: Sturgis
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Williams
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D001707:Biopsy, Needle; D002294:Carcinoma, Squamous Cell / Q000737:chemistry* / Q000401:mortality / Q000556:secondary*; D019941:Cyclin-Dependent Kinase Inhibitor p16; D016208:Databases, Factual; D018572:Disease-Free Survival; D005260:Female; D006258:Head and Neck Neoplasms / Q000737:chemistry / Q000401:mortality / Q000556:secondary / Q000821:virology; D052162:Human papillomavirus 16 / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis*; D009382:Neoplasms, Unknown Primary / Q000737:chemistry* / Q000401:mortality / Q000473:pathology / Q000821:virology; D009959:Oropharyngeal Neoplasms / Q000737:chemistry / Q000401:mortality / Q000556:secondary* / Q000821:virology; D030361:Papillomavirus Infections / Q000235:genetics / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D012878:Skin Neoplasms / Q000737:chemistry* / Q000401:mortality / Q000473:pathology; D016019:Survival Analysis
chemical_list: D014408:Biomarkers, Tumor; C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D009363:Neoplasm Proteins
keywords: cutaneous squamous carcinoma; neck metastases; p16; unknown primary