Ultrastructural features and platelet-derived growth factor receptor A gene mutations in CD117-negative gastrointestinal stromal tumor / 中华病理学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To explore the ultrastructural features and mutation status of platelet-derived growth factor receptors A (PDGFRA) and c-kit in gastrointestinal stromal tumors that were immunohistochemically negative for CD117 antigen.</p><p><b>METHODS</b>Six cases of gastrointestinal stromal tumors that were CD117 immunostain negative were studied by electron microscopy. Direct PCR sequencing was used to investigate the mutation status of c-kit gene exons 9, 11, 13, 17 and PDGFRA gene exons 12 and 18.</p><p><b>RESULTS</b>The ultrastructural features of all 6 cases were similar to those of the interstitial cell of Cajal (ICC). None of the 6 cases were found to have c-kit gene mutations. However, three tumors were found to harbor PDGFRA exon 18 activating mutations, including two tumors having an Asp-->Val842 missense mutation and one having an Arg-->Ser841 missense mutation.</p><p><b>CONCLUSIONS</b>PDGFRA mutations may provide an important alternative molecular mechanism for the development of gastrointestinal stromal tumor.</p>