A 60-year-old man undergoes gastrectomy for a bleeding gastric tumour. Histology shows spindle-shaped cells arising from the muscularis propria, positive for CD117 and DOG1 on immunohistochemistry. Which statement is correct regarding this tumour?
- A Nodal dissection is the mainstay of treatment because spread is primarily lymphatic
- B It arises from smooth muscle and responds to cisplatin-based chemotherapy
- C It arises from interstitial cells of Cajal and activating KIT mutations are common ✓
- D It is negative for CD117 but positive for desmin and S100
Correct answer: C. It arises from interstitial cells of Cajal and activating KIT mutations are common
Explanation
GISTs arise from the interstitial cells of Cajal and most carry activating mutations of KIT (CD117) or PDGFRA, making imatinib mesylate the targeted therapy for unresectable or metastatic disease. Spread is haematogenous and by peritoneal seeding rather than lymphatics, so routine nodal dissection is unnecessary. Desmin and S100 positivity defines leiomyoma and schwannoma respectively, which are the differential diagnoses that option D represents.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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