We observed that a metastatic GIST tumor harbored two different KIT mutations, including a deletion mutation in exon 11 (c.1675_1695del) and a missense mutation in exon 17 (c.G2446C, p. D816H), suggesting that acquired mutation in exon 17 occurred in the metastatic tumor compared with the primary tumor. The gene discussed is KIT; the disease is gastrointestinal stromal tumor.