title: Intra- and inter-observer agreement in histological assessment of canine soft tissue sarcoma.
abstract: BACKGROUND
  The diagnosis of canine soft tissue sarcoma (STS) is based on histological assessment. Assessment of criteria such as, degree of differentiation, necrosis score and mitotic score, gives rise to a final tumour grade, which is important in the recommendation of treatment and prognosis of patients.
  
  
  METHODS
  Previously diagnosed cases of STS were independently assessed by three board-certified veterinary pathologists. Participating pathologists were blinded to the original results. For the intra-observer study, the cases were assessed by a single pathologist six months apart and slides were randomized between readings. For the inter-observer study, the whole case series was assessed by a single pathologist before being passed onto the next pathologist. Intraclass correlation coefficient (ICC) and Fleiss's Kappa (ƙ) for the intra- (single observer) and inter-observer agreement.
  
  
  RESULTS
  Strong agreement was observed for the intra-observer assessment in necrosis score, mitotic score, total score and tumour grading (ICC between 0.78 to 0.91). The intra-observer agreement for differentiation score was rated perfect (ICC 1.00). The agreement between pathologists for the diagnosis and grading of canine STS was moderate (ƙ = 0.60 and 0.43 respectively).
  
  
  CONCLUSIONS
  Histological assessment of canine STS had high reproducibility by an individual pathologist. The agreement of diagnosis and grading of canine STS was moderate between pathologists. Future studies are required to investigate further assessment criteria to improve the specificity of STS diagnosis and the accuracy of the STS grading in dogs.
authors.affiliation: Small Animal Centre, Animal Health Trust, Suffolk, UK.
authors.forename: F W
authors.initials: FW
authors.lastname: Yap
authors.affiliation: DWR Diagnostics, Dick White Referrals, Suffolk, UK.
authors.forename: R
authors.initials: R
authors.lastname: Rasotto
authors.affiliation: Department of Pathology and Pathogen Biology, The Royal Veterinary College, Hatfield, UK.
authors.forename: S L
authors.initials: SL
authors.lastname: Priestnall
authors.affiliation: Small Animal Hospital, Langford Veterinary Services, University of Bristol, Bristol, UK.
authors.forename: K J
authors.initials: KJ
authors.lastname: Parsons
authors.affiliation: Diagnostic Laboratory Services, Animal Health Trust, Suffolk, UK.
authors.forename: J
authors.initials: J
authors.lastname: Stewart
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000175:diagnosis / Q000473:pathology*; D004285:Dogs; D009367:Neoplasm Staging / Q000662:veterinary; D015588:Observer Variation; D012509:Sarcoma / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D012983:Soft Tissue Neoplasms / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*
keywords: canine; histology; inter-observer agreement; intra-observer agreement; soft tissue sarcoma; tumour grading