These tumours are currently defined by having no mutations in exons 9, 11, 12, 13, 17 and 18 of c-kit and exons 12, 14 and 18 of PDGFRA. In the present study, there were four c-kit exon 11 mutations in the five patients with GISTs alone, which is consistent with other studies, but there were only such mutations in two of six cases of synchronous adenocarcinoma with GIST. The gene discussed is PDGFRA; the disease is adenocarcinoma.