The inclusion of KIT/PDGFRA molecular analysis in the diagnostic work-up of all GISTs is highly recommended but as a minimum, such analysis should be performed on all the following specimens: resected moderate or high-risk GISTs at any site; resected GISTs showing tumour rupture; biopsies diagnostic of GIST prior to neoadjuvant or adjuvant therapy; specimens from patients with unresectable and/or metastatic GIST; GISTs which are suspected to be syndromic. This evidence concerns the gene KIT and gastrointestinal stromal tumor.