MCTs with an ITD in c-kit exon 11 were significantly (p = 0.002) associated with a higher Patnaik grading (grade II/III) compared with Patnaik grade I. Furthermore, the relationship between the presence of an ITD in c-kit exon 11 and the classification of the tumour as Kiupel high-grade was significant (p < 0.001). The gene discussed is KIT; the disease is neoplasm.