title: Molecular pathology of skin neoplasms of the head and neck.
abstract: BACKGROUND
  Skin neoplasms include the most common malignancies affecting humans. Many show an ultraviolet (UV)-induced pathogenesis and often affect the head and neck region.
  
  
  OBJECTIVE
  To review literature on cutaneous neoplasms that show a predilection for the head and neck region and that are associated with molecular alterations.
  
  
  METHODS
  Literature review.
  
  
  CONCLUSIONS
  Common nonmelanoma skin cancers, such as basal and squamous cell carcinomas, show a UV-induced pathogenesis. Basal cell carcinomas are characterized by molecular alterations of the Hedgehog pathway, affecting patched and smoothened genes. While squamous cell carcinomas show UV-induced mutations in several genes, driver mutations are only beginning to be identified. In addition, certain adnexal neoplasms also predominantly affect the head and neck region and show interesting, recently discovered molecular abnormalities, or are associated with hereditary conditions whose molecular genetic pathogenesis is well understood. Furthermore, recent advances have led to an increased understanding of the molecular pathogenesis of melanoma. Certain melanoma subtypes, such as lentigo maligna melanoma and desmoplastic melanoma, which are more often seen on the chronically sun-damaged skin of the head and neck, show differences in their molecular signature when compared to the other more common subtypes, such as superficial spreading melanoma, which are more prone to occur at sites with acute intermittent sun damage. In summary, molecular alterations in cutaneous neoplasms of the head and neck are often related to UV exposure. Their molecular footprint often reflects the histologic tumor type, and familiarity with these changes will be increasingly necessary for diagnostic and therapeutic considerations.
authors.affiliation: From the Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (Dr Kraft); and the Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts (Dr Granter).
authors.forename: Stefan
authors.initials: S
authors.lastname: Kraft
authors.forename: Scott R
authors.initials: SR
authors.lastname: Granter
mesh_terms: D001478:Basal Cell Nevus Syndrome / Q000235:genetics / Q000473:pathology; D003528:Carcinoma, Adenoid Cystic / Q000235:genetics / Q000473:pathology; D002280:Basal Cell Carcinoma / Q000209:etiology / Q000235:genetics / Q000473:pathology; D015266:Carcinoma, Merkel Cell / Q000235:genetics / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000209:etiology / Q000235:genetics / Q000473:pathology; D005260:Female; D018859:Hair Follicle / Q000473:pathology; D006258:Head and Neck Neoplasms / Q000209:etiology / Q000235:genetics* / Q000473:pathology*; D053823:Hedgehog Proteins / Q000235:genetics; D018219:Histiocytoma, Benign Fibrous / Q000235:genetics / Q000473:pathology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000235:genetics; D008297:Male; D008545:Melanoma / Q000209:etiology / Q000235:genetics / Q000473:pathology; D009154:Mutation; D018296:Pilomatrixoma / Q000235:genetics / Q000473:pathology; D012307:Risk Factors; D012626:Sebaceous Gland Neoplasms / Q000235:genetics / Q000473:pathology; D015398:Signal Transduction / Q000235:genetics; D012878:Skin Neoplasms / Q000209:etiology / Q000235:genetics* / Q000473:pathology*; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D053823:Hedgehog Proteins