A 55-year-old man undergoes endoscopy showing a 3 cm submucosal antral mass with smooth overlying mucosa. Endoscopic ultrasound reveals a hypoechoic mass arising from the muscularis propria layer. Immunohistochemistry shows CD117 (KIT) positivity. What is the diagnosis?
- A Leiomyoma
- B Gastrointestinal stromal tumor (GIST) ✓
- C Schwannoma
- D Gastric lymphoma
Correct answer: B. Gastrointestinal stromal tumor (GIST)
Explanation
GIST is the most common mesenchymal tumor of the GI tract, typically arising from the muscularis propria and showing CD117 (KIT) positivity in 95% of cases. Leiomyomas are rare in the stomach and are CD117 negative (SMA and desmin positive). Schwannomas are S100 positive. Lymphomas are epithelial/mucosal lesions, not submucosal masses from the muscularis propria.
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.