title: Morphological and immunohistochemical characterisation of seminomas in Norwegian dogs.
abstract: BACKGROUND
  Seminomas in the dog have traditionally been assumed to resemble human spermatocytic seminomas, based on their low malignancy and high occurrence in old individuals. However, recently published studies indicate that canine seminomas can be classified as classical and spermatocytic seminomas in a similar way as in man, and that classical seminomas comprise a substantial proportion of seminomas in the dog. These two factors both contribute to increasing the potential of canine seminoma as a relevant model for human testicular cancer. The aim of the present study was to characterise seminoma in Norwegian dogs using morphology and immunohistochemistry, and determine whether these tumours are comparable with human classical seminoma.
  
  
  METHODS
  By applying diagnostic criteria from human pathology, 45 seminomas from the Norwegian Canine Cancer Register were examined histologically with hematoxylin and eosin (HE) and periodic acid-Schiff (PAS) stains. All sections were stained immunohistochemically with antibodies against human placental alkaline phosphatase (PLAP) and the transmembrane receptor c-KIT.
  
  
  RESULTS
  Although two of the seminomas showed immunohistochemical staining characteristics indicative of classical seminoma (PLAP+/c-KIT+), all 45 examined seminomas were morphologically consistent with spermatocytic seminoma.
  
  
  CONCLUSIONS
  The value of canine seminoma as a model for SE in man remains unclear. Among the 45 investigated tumours from Norwegian dogs, none were classified as classical seminoma based on morphological criteria consistent with human seminomas. Regional or breed differences in the occurrence of classical seminoma in the dog, as well as the lack of uniform diagnostic criteria, might explain the discrepancy between the findings in the current study and the results presented by other authors.
authors.affiliation: Department of Companion Animal Clinical Sciences, Norwegian School of Veterinary Science, PO Box 8146 Dep, 0033, Oslo, Norway.
authors.forename: Tor Espen
authors.initials: TE
authors.lastname: Thorvaldsen
authors.forename: Ane
authors.initials: A
authors.lastname: Nødtvedt
authors.forename: Tom
authors.initials: T
authors.lastname: Grotmol
authors.forename: Gjermund
authors.initials: G
authors.lastname: Gunnes
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D003430:Cross-Sectional Studies; D004195:Disease Models, Animal; D004285:Dogs; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D009664:Norway; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D018239:Seminoma / Q000175:diagnosis / Q000473:pathology* / Q000662:veterinary*; D013736:Testicular Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000662:veterinary*
chemical_list: D007527:Isoenzymes; C055791:germ-cell AP isoenzyme; D019009:Proto-Oncogene Proteins c-kit; D000469:Alkaline Phosphatase