title: Histological characteristics of metastasizing thin melanomas: a case-control study of 43 cases.
abstract: OBJECTIVE
  To study clinical and histological features associated with metastasizing thin melanomas (MTMs).
  
  
  METHODS
  Case-control study of clinicopathological features of patients with MTMs by a panel of 10 dermatopathologists.
  
  
  METHODS
  Members of the North American Melanoma Pathology Study Group selected the cases from the melanoma databases at 8 academic institutions.
  
  
  METHODS
  Forty-three patients with MTMs (<1 mm thick) and 42 control subjects without metastasis matched for age, sex, tumor site, and Breslow thickness.
  
  
  METHODS
  None.
  
  
  METHODS
  Clinical (age, sex, site of lesion, stage at diagnosis, metastasis site, disease-free survival, and outcome) and histological (Breslow thickness, Clark level, growth phase, regression, and inflammatory response) features of patients with MTMs vs controls.
  
  
  RESULTS
  There was an overrepresentation of axial tumors among patients with MTMs. Extensive regression was present in 18 patients (42%) with MTM vs 2 matched control subjects (5%) (95% confidence interval, 21%-53%; P =.001). Other histological variables were not significantly different. Two patients had melanomas in situ with subsequent metastasis.
  
  
  CONCLUSIONS
  Thin melanomas with extensive regression represent a group at higher risk for the development of metastasis. Furthermore, the risk of metastasis cannot be dismissed in cases of melanoma in situ.
authors.affiliation: Department of Dermatology, Northwestern University Medical School, 675 N St Clair, Suite 19-150, Chicago, IL 60611, USA. j-guitart@nwu.edu
authors.forename: Joan
authors.initials: J
authors.lastname: Guitart
authors.forename: Lori
authors.initials: L
authors.lastname: Lowe
authors.forename: Michael
authors.initials: M
authors.lastname: Piepkorn
authors.forename: Victor G
authors.initials: VG
authors.lastname: Prieto
authors.forename: Michael S
authors.initials: MS
authors.lastname: Rabkin
authors.forename: Salve G
authors.initials: SG
authors.lastname: Ronan
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Shea
authors.forename: Victor A
authors.initials: VA
authors.lastname: Tron
authors.forename: Wain
authors.initials: W
authors.lastname: White
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Barnhill
mesh_terms: D000328:Adult; D000368:Aged; D002278:Carcinoma in Situ / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000473:pathology*; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D011379:Prognosis; D012075:Remission, Spontaneous; D012307:Risk Factors; D012878:Skin Neoplasms / Q000473:pathology*