A 62-year-old man undergoes endoscopy for anaemia and melena. A large submucosal mass is seen in the gastric body; biopsy shows spindle cells positive for CD117 and DOG1 on immunohistochemistry. CT shows no metastases. Which statement about this tumour is correct?

• A It arises from smooth muscle and is treated primarily with doxorubicin-based chemotherapy
• B It commonly metastasizes to regional lymph nodes, so routine lymphadenectomy is essential
• C Risk of malignant behaviour depends mainly on the depth of mucosal invasion
• D It usually harbours an activating KIT mutation and imatinib mesylate is effective for advanced disease ✓

Explanation

Gastrointestinal stromal tumours arise from the interstitial cells of Cajal and are defined by activating mutations in KIT (about 80 percent) or PDGFRA, giving CD117 positivity. Imatinib, a tyrosine kinase inhibitor, is first-line therapy for unresectable or metastatic disease and as adjuvant therapy in higher-risk resected cases. GISTs rarely involve lymph nodes, so lymphadenectomy is not required; treatment is wedge resection with intact margins. Risk stratification uses tumour size and mitotic rate, not depth of mucosal invasion.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.