Gastrointestinal stromal tumors: Variants and some pitfalls that they create

This article discusses how gastrointestinal stromal tumors (GISTs) are typically diagnosed using histologic evaluation and immunohistochemical staining for CD117/kit and DOG-1. However, diagnosis can be challenging in cases with unusual morphology, limited biopsies, uncommon sites, or post-treatment changes. Testing for succinate dehydrogenase (SDH) deficiency is recommended for epithelioid GISTs, particularly in younger patients. GISTs with PDGFRA mutations or post-treatment alterations, such as loss of kit expression, may also complicate diagnosis. Clinical information on prior tyrosine kinase inhibitor (TKI) therapy is essential.