Gastrointestinal Stromal Tumours (GISTs) with KRAS Mutation: A Rare but Important Subset of GISTs.

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the GI tract, usually found in the stomach, jejunum, and ileum. Typically, they are or -mutated, allowing for targetable treatments with tyrosine kinase inhibitors such as imatinib. Here, we present two -mutated wild-type gastrointestinal tumours (GISTs). Both cases occurred in the small bowel of females. Immunohistochemical studies on both tumours showed KIT and DOG-1 positivity, with SDHB retained. Molecular analysis revealed a mutation and a mutation, respectively. Wild-type GISTs are extremely uncommon. They typically occur in the stomach or the small bowel. is one of the genes implicated in this subset of GIST, with being the most frequently encountered mutation. GIST mutations can arise alone or in conjunction with , or mutations. Identification of these rare molecular subtypes is clinically important due to their resistance to imatinib therapy.