title: Biology of desmoplastic melanoma: a case-control comparison with other melanomas.
abstract: OBJECTIVE
  Previous studies have established that patients with desmoplastic melanoma (DM) have thicker primary tumors. Consequently, comparisons with other forms of melanoma have been strongly biased by differences in Breslow stage. This is the first case-matched control study comparing DM with other forms of melanoma.
  
  
  METHODS
  From a database of 3,202 melanoma patients treated at one institution, 89 patients with DM and 178 case-matched control patients (2:1) were identified by matching for tumor thickness, age, sex, and year of diagnosis. Clinical, pathologic, and outcome information was obtained from chart review.
  
  
  RESULTS
  Controls were matched successfully to patients for tumor thickness, age, sex, and year of diagnosis. Presentation with American Joint Committee on Cancer stage III or IV disease is less common in patients with DM compared to case-matched control patients (5% v 21%; P < .001). Re-excisions to obtain clear surgical margins are required more often in patients with DM compared to case-matched control patients (21% v 6%; P < .001). Risk of positive sentinel nodes is lower in patients with DM compared to case-matched control patients (8% v 34%; P = .013). Despite these differences, survival rates of patients with DM are the same as case-matched control patients.
  
  
  CONCLUSIONS
  Use of case-matched control patients matched for tumor thickness avoids biases introduced by the advanced Breslow stage of DMs. DMs are more locally aggressive than thickness-matched controls, and positive sentinel nodes are limited to patients with thick primary tumors. Importantly, patients with DM have survival rates similar to patients with other melanomas of similar thickness.
authors.affiliation: Department of Surgery, Massachusetts General Hospital, Boston, MA 02114, USA.
authors.forename: Daan P
authors.initials: DP
authors.lastname: Livestro
authors.forename: Alona
authors.initials: A
authors.lastname: Muzikansky
authors.forename: Emily M
authors.initials: EM
authors.lastname: Kaine
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Flotte
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Sober
authors.forename: Martin C
authors.initials: MC
authors.lastname: Mihm
authors.forename: James S
authors.initials: JS
authors.lastname: Michaelson
authors.forename: A Benedict
authors.initials: AB
authors.lastname: Cosimi
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Tanabe
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D015994:Incidence; D008198:Lymph Nodes / Q000473:pathology*; D008297:Male; D008545:Melanoma / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology / Q000473:pathology*; D009367:Neoplasm Staging; D011336:Probability; D011379:Prognosis; D012016:Reference Values; D012189:Retrospective Studies; D018570:Risk Assessment; D021701:Sentinel Lymph Node Biopsy; D017678:Sex Distribution; D012878:Skin Neoplasms / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D018709:Statistics, Nonparametric; D015996:Survival Rate