[Phenotypic Change in a Gastric GIST after NAC‒Imatinib-A Case Report]

The patient was a 53‒year‒old man who presented to our hospital for evaluation of epigastric pain. Gastroscopy revealed a submucosal tumor with delle. Biopsy specimens showed spindle cell proliferation in a palisading pattern, and immunohistochemical staining(IHC)was positive for c‒kit, leading to a diagnosis of GIST. We underwent surgical resection after NAC and achieved a complete resection. The histopathological findings from the resected specimen differed markedly from the biopsy specimen, making the postoperative diagnosis difficult. There have been few reports on the IHC change in cases of GIST after NAC, so we report this case and provide a literature review.