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

Figure 1

Case 1: the tumour formed a well-circumscribed, intramural mass with intact overlying mucosa (a). It was composed of spindle and epithelioid cells arranged in interlacing fascicles (b). Occasional bizarre, larger multinucleated cells were also present scattered throughout the lesion (c). Focally, there were areas of oedema and microcystic change (d). Immunohistochemistry showed intense, diffuse positivity for CD117 (KIT) (e) and DOG-1 (f).