Peer-reviewed veterinary case report
Comparing 2-tier and 3-tier grading for dog mast cell tumors survival
By Sabattini, S et al.·Published in Veterinary pathology·2015·Department of Veterinary Medical Sciences, Italy·View original on PubMed →
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Original publication title: Histologic grading of canine mast cell tumor: is 2 better than 3?
- Species:
- dog
Plain-English summary
A group of dogs with mast cell tumors (MCTs), a type of skin cancer, were studied to see how well two different grading systems could predict their survival. The older Patnaik grading system categorized tumors into three grades, while a newer two-tier system simplified this to just two grades. The study found that dogs with grade III tumors had a much poorer prognosis compared to those with grade I tumors, while many grade II tumors had a good survival rate. The two-tier system proved to be effective in predicting outcomes, but it was noted that grading alone can't fully determine how aggressive a tumor might be.
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Abstract
Mast cell tumor (MCT) is a common canine cutaneous neoplasm with variable biological behavior. A 2-tier histologic grading system was recently proposed by Kiupel et al to reduce interobserver variation and eliminate prognostic uncertainty of the Patnaik system. This study compared the ability of these 2 grading systems to predict survival in a cohort of dogs with MCTs. However, surgical margins were unknown, and the risk of developing new/metastatic MCTs was not studied. Histologic grade was assessed according to both systems for 137 surgically resected cutaneous MCTs. The relationship between grade and survival was evaluated. According to the Patnaik system, 18 MCTs (13.1%) were classified as grade I, 83 (60.6%) as grade II, and 36 (26.3%) as grade III. Grade III was associated with a poorer prognosis (P < .001), but no significant difference between grades I and II was detected. Grading according to the Patnaik system was based on consensus grading among 3 pathologists, and interobserver variability was not considered. All grade I MCTs were low grade in the Kiupel system, and all grade III were high grade. Among grade II, 71 (85.6%) were low grade, and 12 (14.4%) were high grade, with a 1-year survival probability of 94% and 46%, respectively (P < .001). The 2-tier system had a high prognostic value and was able to correctly predict the negative outcomes of some grade II MCTs. Data also confirm that histologic grading cannot predict biological behavior of each MCT and should be supplemented with molecular methods for more accurate prognostication.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/24513799/