<prompt> Gold standard investigation for recurrent gastrointestinal stromal tumor isMRIMIBGUSGPET CT  <response>: .Investigation: - Mainly CT scan - Tumour molecular marker to differentiate it from sarcomas immunohistochemistry. - Endosonography guided biopsyguided FNAC are impoant to get histological confirmation. - 18 FDG PET scan is very useful adjunct to CT but reserved for difficultequivocal cases. ref:SRB;S manual of surgery,ed 3,pg no 792 