title: Progression of skin lesions from normal skin to squamous cell carcinoma.
abstract: OBJECTIVE
  To assess the changes in the nuclear chromatin pattern concomitant with progressive sun damage in skin biopsies ranging from sun-exposed, normal-appearing skin to squamous cell carcinoma (SCC).
  
  
  METHODS
  Biopsies were taken from 140 cases with sun-exposed but histopathologically normal skin, from 20 cases visually assessed as pre-actinic keratosis (pre-AK) or early AK, from 30 cases of AK, and from 21 cases of SCC. A total of 21,094 nuclei were recorded from these biopsies. High-resolution digital imagery was recorded, and features descriptive of the nuclear chromatin pattern were computed. Both supervised learning and unsupervised learning algorithms were employed to derive progression plots.
  
  
  RESULTS
  With increased sun exposure, the proportion of nuclei exhibiting changes in the nuclear chromatin pattern rises notably. Using karyometry, no significant differences could be substantiated between nuclei collected from early AK sites and AK lesions. Cases of SCC fell into 2 distinct groups. A larger group (approximately 66.7% of cases) had characteristics similar to AK. A smaller group (approximately 33.3% of cases) represented much more progressed lesions.
  
  
  CONCLUSIONS
  Karyometric assessment can provide a numeric measure of progression for sun damage and of the deviation from normal in both AK and SCC lesions.
authors.affiliation: Southern Arizona Veterans Affairs Health Care System, Tucson, Arizona, USA.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Krouse
authors.forename: David S
authors.initials: DS
authors.lastname: Alberts
authors.forename: Anil R
authors.initials: AR
authors.lastname: Prasad
authors.forename: Michael
authors.initials: M
authors.lastname: Yozwiak
authors.forename: Hubert G
authors.initials: HG
authors.lastname: Bartels
authors.forename: Yun
authors.initials: Y
authors.lastname: Liu
authors.forename: Peter H
authors.initials: PH
authors.lastname: Bartels