H3.3 alterations are also reported in only 1/75 conventional or dedifferentiated cartilaginous tumors and are mutually exclusive of isocitrate dehydrogenase (IDH) type 1 or IDH2 substitutions which occur in 60 % of conventional or dedifferentiated cartilaginous tumors [11, 17]). This evidence concerns the gene IDH2 and chondrogenic neoplasm.