PDGFRB and neoplasm: Mutation analysis performed on the progressive tumor nodule before start of regorafenib showed the same p.(M844_S847del) (c.2531_2542del) mutation in exon 18 of PDGFRα as detected in the primary tumor, whereas no additional mutations were found in exon 12 and 14 of PDGFRΑ nor in exon 9, 11, 13, 14, 17 of KIT (the average coverage is ∼2000 reads in tumor DNA with neoplastic content of 80%).