CDK4 and gastrointestinal stromal tumor: Similarly, in this study, we found that the majority of referral cases had appropriate immunohistochemistry tests performed but that, in 23 cases, additional immunohistochemical tests contributed to the cases of diagnostic discrepancy of which the commonest antibodies omitted at referral centres were h-caldesmon for leiomyosarcoma, CDK4 for WDL/DDL, DOG1 for GIST, and beta-catenin for fibromatosis.