A 62-year-old woman undergoes wedge resection of a 7 cm gastric mass arising from the muscularis propria. Histology shows spindle cells arranged in fascicles. Which marker confirms gastrointestinal stromal tumour and which targeted agent is used when the disease recurs?

• A CD34 positivity, treated with sunitinib
• B Desmin positivity, treated with doxorubicin
• C S100 positivity, treated with sorafenib
• D KIT (CD117) positivity, treated with imatinib ✓

Explanation

About 85 to 90 percent of gastrointestinal stromal tumours harbour activating KIT mutations and show strong cytoplasmic CD117 staining; a further subset carries PDGFRA mutations. Imatinib, a tyrosine kinase inhibitor targeting KIT, is standard for advanced or recurrent disease and also given adjuvantly for high-risk resected tumours. Desmin marks smooth muscle tumours such as leiomyosarcoma, and S100 marks schwannomas, the main mimics on biopsy.

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.