DDSEP® 8 Quick Quiz

Question 2

Q2. A 65-year-old man undergoes upper endoscopy for epigastric discomfort. The exam results are normal, except for a 3-cm submucosal mass in the body of the stomach. Endoscopic ultrasound shows that the mass arises from the fourth layer of the stomach wall. CT of the abdomen confirms the solid gastric mass with several small lesions in the liver concerning for metastatic disease. Biopsy of the mass shows CD117-positive spindle cells.

Which of the following is true about this tumor?

Small intestine is the most common location

KIT negative

Worse prognosis for tumors located in the stomach

Treatment for recurrent or metastatic disease is imatinib

Q2. Correct answer: D. Treatment for recurrent or metastatic disease is imatinib.


Rationale
This patient has a gastrointestinal stromal tumor (GIST) of the stomach. GISTs are the most common mesenchymal tumor found in the stomach. Gastric GISTs have a better prognosis than those found in the small intestine. GISTs are often found incidentally but can cause symptoms such as bleeding due to ulceration. Pathology of a GIST shows spindle cells that stain positive for CD117 and harbor KIT mutations. Malignant potential and decreased survival are associated with size more than 2 cm and high mitotic index (more than 5/50 high power field). Endoscopic ultrasound with tissue sampling is the preferred diagnostic technique. High-risk features include lobulated or irregular borders, invasion into adjacent structures and heterogeneity. Fine needle aspirate may be suboptimal, and core biopsy is an acceptable alternative. Resection is indicated for lesions that are symptomatic, size more than 2 cm or high-risk EUS features. Lesions less than 2 cm without high-risk features can be surveyed by EUS annually. Endoscopic resection might be possible for small lesions but should be done in specialized centers. Metastatic or recurrent lesions are treated with imatinib.

Reference
ASGE Standards of Practice Committee. Gastrointest Endosc. 2015 Jul;82(1):1-8.

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