title: Assessment of tumor mitotic rate in primary cutaneous malignant melanomas 1 mm or less in thickness.
abstract: BACKGROUND
  Tumor mitotic rate in thin melanomas is recognized as a powerful, independent prognostic factor predicting survival. In nonulcerated cases, the presence of any dermal mitotic activity upstages the disease to pT1b. The extent to which tissue should be histologically examined to assess mitogenicity, however, has not been studied.
  
  
  OBJECTIVE
  We sought to determine whether in staging thin melanomas, there is a significant benefit in examining numerous tissue sections containing invasive disease.
  
  
  METHODS
  In all, 71 cases of thin cutaneous melanomas diagnosed between January 2012 and June 2013 were identified after a search performed on the Pathlab database. The slides were retrieved and reviewed retrospectively, comparing the identification of the first dermal tumor mitotic figure, if present, at 4 check-points: the first, third, fifth, or tenth tissue section examined.
  
  
  RESULTS
  A statistically significant difference in identification of the first dermal mitotic figure was found in examining 1 versus 3 tissue sections (P = .0411). No significant difference was found in examining numerous tissue sections.
  
  
  CONCLUSIONS
  This was a retrospective study from a single institution with a limited number of participants.
  
  
  CONCLUSIONS
  In staging thin melanomas without ulceration, the optimal number of sections to assess is 3. No additional benefit is gained by examining numerous tissue sections.
authors.affiliation: Dermatopathology Section, Pathlab Bay of Plenty, Tauranga, New Zealand. Electronic address: cywshin@gmail.com.
authors.forename: Christina
authors.initials: C
authors.lastname: Shin
authors.affiliation: Dermatopathology Section, Pathlab Bay of Plenty, Tauranga, New Zealand; DaVinci Clinic, Tauranga, New Zealand.
authors.forename: Ben
authors.initials: B
authors.lastname: Tallon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology*; D008875:Middle Aged; D008938:Mitosis; D012189:Retrospective Studies; D012878:Skin Neoplasms; D047368:Tumor Burden; D000096142:Cutaneous Malignant Melanoma
keywords: hot spot method; malignant melanoma; prognostic factor; thin melanoma; tissue sections; tumor mitotic rate