title: Histologic prognosticators in feline osteosarcoma: a comparison with phenotypically similar canine osteosarcoma.
abstract: OBJECTIVE
  To investigate the histologic characteristics of feline osteosarcoma (OS) and compare the histologic data with phenotypically comparable canine OS. The effects of histologic and clinical variables on survival statistics were evaluated.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  Cats (n=62) and dogs (22).
  
  
  METHODS
  Medical records of 62 cats with OS were reviewed for clinically relevant data. Clinical outcome was obtained by telephone interview. Histologic characteristics of OS were classified using a standardized grading system. Histologic characteristics in 22 feline skeletal OS were compared with 22 canine skeletal OS of identical location and subtype. Prognostic variables for clinical outcome were determined using multivariate analysis.
  
  
  RESULTS
  Feline OS was characterized by moderate to abundant cellular pleomorphism, low mitotic index, small to moderate amounts of matrix, high cellularity, and a moderate amount of necrosis. There was no significant difference between histologic variables in feline and canine OS. Histologic grade, surgery, and mitotic index significantly influenced clinical outcome as determined by multivariate analysis. Tumor invasion into vessels was not identified as a significant prognosticator.
  
  
  CONCLUSIONS
  Feline and canine skeletal OS have similar histologic but different prognostic characteristics.
  
  
  CONCLUSIONS
  Prognosis for cats with OS is related to histologic grade and mitotic index of the tumor.
authors.affiliation: Department of Small Animal Clinical Sciences, Faculty of Life Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Maria
authors.initials: M
authors.lastname: Dimopoulou
authors.forename: Jolle
authors.initials: J
authors.lastname: Kirpensteijn
authors.forename: Hester
authors.initials: H
authors.lastname: Moens
authors.forename: Marja
authors.initials: M
authors.lastname: Kik
mesh_terms: D000818:Animals; D001859:Bone Neoplasms / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D002371:Cat Diseases / Q000401:mortality / Q000473:pathology*; D002415:Cats; D004283:Dog Diseases / Q000401:mortality / Q000473:pathology*; D004285:Dogs; D005260:Female; D008297:Male; D008940:Mitotic Index / Q000662:veterinary*; D015999:Multivariate Analysis; D009367:Neoplasm Staging / Q000662:veterinary*; D012516:Osteosarcoma / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome