Comparison of KIT patterns and infiltration of eosinophils in canine mast cell tumor

Abstract

KIT protein is associated with the etiology of canine mast cell tumors (MCT); however, the expression patterns of KIT are highly variable. The aim of this study was to determine if KIT patterns are related with eosinophil count in MCT. Hematoxylin eosin and May Grünwald-Giemsa stain techniques were applied, histological grading and eosinophil counting were performed in 48 MCT samples. Immunohistochemical evaluation was performed with IL-5, VEGFr, and c-KIT antibodies. The percentage of immunolabeling with IL-5 and VEGFr was determined, and the samples incubated with c-KIT were graded according to the immunolabeling pattern. Comparison of the mean eosinophil count between the histological grades and the different KIT expression patterns demonstrated a significant difference between KIT pattern 1 and KIT pattern 3, KIT pattern 3 showed a higher mean of eosinophil count. There was no significant correlation between eosinophil count and KIT patterns (p = 0.2648). However, a positive correlation was observed between the KIT patterns and Patnaik and Kiupel grades (p = 0.0006 and p = 0.0267, respectively). There was no significant correlation between eosinophil count, IL-5, or VEGFr. Further studies should determine whether eosinophil counts are an independent predictor of clinical outcome or simply correlated with already known predictors.