Suspect Subepithelial Lesion in the Antrum of a Middle-Aged Man

A 50-year-old man who was scheduled for a colonoscopy also undergoes an upper endoscopy to screen for Barrett esophagus, based on a long history of acid reflux disease. He is incidentally noted to have a 2-cm subepithelial lesion in the antrum (Figure).

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1. What is the next step in evaluation?

A. Endoscopic ultrasound

B.  CT abdomen

C. Surgical resection

D. Observation with repeat endoscopy in 1 year

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Answer: A. Endoscopic ultrasound

Endoscopic ultrasound (EUS) is the next step in evaluation of subepithelial lesions of the stomach. In this case, EUS revealed a hypoechoic lesion arising from the 4th layer (muscularis propria) of the stomach. This narrows the differential diagnosis to predominantly gastrointestinal stromal tumor (GIST) and leiomyoma. Pancreatic rest and lymphomas are also hypoechoic, but more commonly originate from the submucosa and not muscularis propria.

2. Fine-needle aspiration (FNA) of the lesion is performed.  Which of the following markers is diagnostic of GIST tumors?

A. CD34

B. S-100

C. C-kit

D. DOG1

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Answer: C. C-kit

C-kit mutations are present in 80% to 90% of GIST tumors. This mutation causes cell proliferation; the uncontrolled cell growth can lead to a GIST tumor.

3. How would you manage this lesion?

A. Endoscopic resection

B. Surgical resection

C. Surveillance endoscopy in 1 year

D. Radiation therapy

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Answer: B. Surgical resection (Figure)

Management depends on size and mitotic activity of the tumor. For lesions larger than 2 cm, surgical resection is recommended. In addition to surgery, tyrosine kinase inhibitors are used as adjuvant treatment, particularly for lesions larger than 3 cm. Lesions that are smaller than 2 cm have low malignant potential and can undergo surveillance. Interval surveillance recommendations vary, with most centers repeating an imaging study in 1 year. If the lesion remains stable after 2 consecutive exams, then surveillance intervals can be extended.