IDH1 and chondrosarcoma: Molecular analysis of both components was performed in five cases to detect IDH1, IDH2 or H3F3B mutations, in order to elucidate whether areas with clear cell chondrosarcoma morphology represent a phenotypic phenomenon occurring in conventional chondrosarcoma, represent a collision between two types of chondrosarcoma, or should be considered to be clear cell chondrosarcoma with extensive conventional chondrosarcoma areas.