Kit receptor tyrosine kinase dysregulations in feline splenic mast cell tumours

Abstract

This study investigated Ki t receptor dysregulations (cytoplasmic immunohistochemical expression and/or c-KIT mutations) in cats a\ufb00ected with splenic mast cell tumours. Twenty-two cats were included. Median survival time was 780 days (range: 1\u20131219). An exclusive splenic involvement was signi\ufb01cantly (P = 0.042) associated with longer survival (807 versus 120 days). Eighteen tumours (85.7%) showed Kit cytoplasmic expression (Kit pattern 2, 3). Mutation analysis was successful in 20 cases. Fourteen missense mutations were detected in 13 out of 20 tumours (65%). Eleven (78.6%) were located in exon 8, and three (21.6%) in exon 9. No mutations were detected in exons 11 and 17. Seven mutations corresponded to the same internal tandem duplication in exon 8 (c.1245_1256dup). Although the association between Kit cytoplasmic expression and mutations was signi\ufb01cant, immunohistochemistry cannot be considered a surrogate marker for mutation analysis. No correlation was observed between c-Kit mutations and tumour di\ufb00erentiation, mitotic activity or survival