title: Solitary Large Keratoacanthomas of the Head and Neck: An Observational Study.
abstract: BACKGROUND
  Solitary large keratoacanthomas (KAs) of the head and neck present a management dilemma, as no reliable means to predict the clinical course is available. Although typically considered a low-grade tumor, KAs are reported to invade/metastasize, prompting more aggressive treatment. There is little published regarding factors that predict when a KA behaves more like an aggressive squamous cell carcinoma (SCC).
  
  
  OBJECTIVE
  To study the clinical and pathologic features of large solitary head and neck KAs and assess response to intralesional methotrexate (IL-MTX) as well as predictors of clinical course.
  
  
  METHODS
  An observation study of 14 patients with large solitary head and neck KAs were treated with IL-MTX and then excised by Mohs micrographic surgery (MMS) at a later time point. Clinical presentation, treatment, response, and pathology were recorded. Features of classic KAs were compared with those with an aggressive SCC course.
  
  
  RESULTS
  Ten of fourteen lesions responded with necrosis, a decrease in size and/or pain, and histological clearance on MMS. However, 4/14 lesions continued to have progression despite IL-MTX therapy. These showed persistent pain, perineural invasion, moderate/poor differentiation, and an infiltrative growth.
  
  
  CONCLUSIONS
  Small sample size.
  
  
  CONCLUSIONS
  Significant pain, or continued growth may suggest an underlying aggressive SCC in clinically classic large KAs. In these cases, surgical management with assessment for high-risk tumor features is recommended.
authors.affiliation: *Department of Medicine, Dermatology Service, Memorial Sloan Kettering Cancer Center, New York, New York; †Weill Cornell Medicine, New York, New York; ‡Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Rossi
authors.forename: Brian
authors.initials: B
authors.lastname: Park
authors.forename: Bernice
authors.initials: B
authors.lastname: Qi
authors.forename: Erica H
authors.initials: EH
authors.lastname: Lee
authors.forename: Klaus J
authors.initials: KJ
authors.lastname: Busam
authors.forename: Kishwer S
authors.initials: KS
authors.lastname: Nehal
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage*; D003131:Combined Modality Therapy; D005260:Female; D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery*; D006801:Humans; D015552:Injections, Intralesional; D007636:Keratoacanthoma / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery*; D008297:Male; D008727:Methotrexate / Q000008:administration & dosage*; D008875:Middle Aged; D015580:Mohs Surgery; D011446:Prospective Studies; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery*
chemical_list: D000964:Antimetabolites, Antineoplastic; D008727:Methotrexate