Gastroenterology and Hepatology Board Review: Pearls of Wisdom, Third Edition

Section III STOMACH

CHAPTER 17. Gastric Tumors

Douglas O. Faigel, MD

Image What is the most common type of malignant tumor of the stomach?

Adenocarcinoma comprises 90% of all cases. Less common malignant neoplasms include lymphoma, stromal tumor, carcinoid, adenosquamous, and metastases.

Image What are the two main histological types of gastric adenocarcinoma?

Intestinal type and diffuse type.

Image Germline mutations in which gene have been associated with diffuse type gastric adenocarcinoma?

E-cadherin.

Image True/False: Helicobacter pylori plays a role in the etiology of gastric cancer.

True. H. pylori results in chronic gastritis which, presumably, may proceed to metaplasia, dysplasia, and cancer. It has been classified as a Class A carcinogen by the World Health Organization.

Image What is a Krukenberg tumor?

Gastric cancer metastatic to the ovary.

Image What are the two most common sites of gastric cancer metastasis?

The liver and lungs constitute about 40% of total cases.

Image True/False: Most gastric cancer patients have signs of overt GI bleeding such as melena or hematemesis.

False. Less than 20% have overt GI bleeding.

Image True/False: Gastric ulcers require endoscopic follow-up to document healing.

True. However, it has been suggested that extensive biopsies from the ulcer taken at the time of the initial endoscopy may obviate the need for follow-up endoscopy, if the biopsies were negative/not suspicious for malignancy.

Image A 64-year-old man with gastric cancer presents with velvety, pigmented lesion in the axilla. What is the diagnosis?

Acanthosis nigricans is considered a paraneoplastic manifestation.

Image True/False: Endoscopic ultrasound (EUS) is the best modality to assess the extent of local disease in gastric cancer.

True. This can be combined with a CT scan to allow for complete staging.

Image What is the best prognostic factor in gastric cancer?

The TNM (Tumor, Node, Metastasis) stage at the time of diagnosis.

Image A patient with gastric adenocarcinoma undergoes EUS which demonstrates invasion into the left lobe of the liver. What is the T-stage?

Image

Figure 17-1

Invasion of an adjacent organ is T4.

Image What treatment has the best curative potential for gastric adenocarcinoma?

Surgical resection. Unfortunately, two-thirds of Western patients present with advanced disease and are not surgical candidates for cure.

Image True/False: Perioperative chemoradiotherapy improves outcome in gastric adenocarcinoma?

True. Three recent studies of perioperative chemoradiotherapy and at least four meta-analyses have shown improved disease-free and overall survival in the treated groups.

Image What is the most common type of gastric malignancy after adenocarcinoma?

Primary gastric lymphoma.

Image What are the two most common types of gastric lymphoma?

Diffuse large B cell lymphoma and low-grade B cell mucosa-associated lymphoid tissue (MALT) lymphoma.

Image True/False: H. pylori is associated with gastric lymphoma.

True. Ninety percent of low-grade MALT lymphomas are positive for H. pylori. Additionally, tumor remission has been documented after eradication of H. pylori in a number of cases.

Image True/False: A 45-year-old man is found to have a B-cell lymphoma of the stomach. Based on the EUS image shown, he is likely to respond to anti-H. pylori therapy.

Image

Figure 17-2

False. The EUS shows diffuse and deep invasion of the gastric wall. This is consistent with an aggressive diffuse large B-cell lymphoma. Antibiotic therapy would be inadequate.

Image What part of the gastrointestinal tract is the most common site for a primary gastrointestinal lymphoma?

The stomach is the site in 70% or more of the cases. The remaining cases are equally divided between the small and large intestine.

Image A 62-year-old woman with abdominal pain undergoes endoscopy and a submucosal tumor is found (see Figures 17-3 and 17-4). What is the most likely diagnosis based on the EUS image shown?

Image

Figure 17-3

Image

Figure 17-4 See also color plate.

Gastrointestinal stromal tumor (GIST).

Image True/False: Discovered on GIST-1 (DOG1) is the most commonly used immunohistochemical marker for GIST.

False. cKit is the most commonly used marker. DOG1 is reserved for suspicious tumors that are cKit negative.

Image What proportion of GISTs are located in the stomach?

Fifty percent. Most are in the proximal portion of the stomach.

Image What is the Carney triad?

Gastric stromal tumor, extra-adrenal paraganglioma, and pulmonary chondroma.

Image Which features of a gastric stromal tumor indicate a higher likelihood of recurrence after resection?

The mitotic index of 5 or more mitoses per 50 high-power fields, and size ≥5 cm.

Image Which patients have a higher incidence of gastric carcinoid?

Patients with hypergastrinemia as occurs in pernicious anemia, atrophic gastritis with achlorhydria and Zollinger–Ellison syndrome.

Image True/False: Gastric carcinoids are grouped into two categories (type 1 and type 2).

False. Gastric carcinoids are grouped into three categories: those associated with atrophic gastritis (type 1), gastrinoma or multiple endocrine neoplasia (type 2), and neither (type 3).

Image True/False: Treatment of gastric carcinoid differs depending on the type.

True. Types 1 and 2 smaller than 1 cm are generally amenable to endoscopic resection, while type 3 (sporadic) gastric carcinoids require more extensive gastric resection.

Image True/False: The stomach is the most common site for GI neuroendocrine tumors (carcinoids)?

False. Less than 5% of GI neuroendocrine tumors (carcinoids) are found in the stomach.

Image True/False: Thickened folds of the stomach may be caused by metastatic breast cancer.

True. Although breast cancer, like other types of cancer, may metastasize to the stomach causing a focal mass lesion, infiltration and thickening of the gastric folds as shown in the figure may also occur in breast cancer. This appearance is indistinguishable from other infiltrating tumors such as diffuse-type gastric adenocarcinoma and high-grade lymphoma.

Image What is the most common location for a gastric lipoma?

The antrum. These are benign submucosal tumors. EUS is very useful for differentiation from other tumors.

Image What are the two most common types of gastric polyps?

Hyperplastic polyps and fundic gland polyps. Together, they represent 70%–90% of all gastric polyps.

Image A 73-year-old woman with a history of melanoma undergoes upper endoscopy and a brownish-black nodule is present in the stomach. What is the diagnosis?

Image

Figure 17-5

Metastatic melanoma involving the stomach.

Image True/False: There is an association between fundic gland polyps and familial adenomatous polyposis (FAP).

True. More than 60% of FAP patients have fundic gland polyps.

Image True/False: Fundic gland polyps may be seen in patients on chronic proton pump inhibitor (PPI) therapy.

True. Up to one-third of long-term users of PPIs have fundic gland polyps. The risk of histologic progression is negligible.

Image What conditions are associated with hyperplastic polyps of the stomach?

Atrophic gastritis and H. pylori infection.

Image What is the most likely diagnosis of a 2-cm antral nodule with a central dimple?

Pancreas rest (ectopic pancreatic tissue). This constitutes about 1% of gastric polyps.

Image What is the only benign gastric polyp with significant malignant potential?

Adenomatous polyp.

Image True/False: The presence of invasive cancer in an adenoma correlates with size, villous histology, and degree of dysplasia.

True.

Image True/False: All gastric polyps should be biopsied and removed if possible.

True. If multiple, a representative sample of polyps should be biopsied and the pathology identified. Those >1 cm should be removed whenever possible.

Image True/False: Because adenomatous and hyperplastic polyps are associated with atrophic gastritis and H. pylori infection, the normal appearing antral and body mucosa should also be sampled.

True.

• • • SUGGESTED READINGS • • •

Hirota WK, Zuckerman MJ, Adler DG, et al. Standards of Practice Committee American Society for Gastrointestinal Endoscopy. ASGE guideline: the role of endoscopy in the surveillance of premalignant conditions of the upper GI tract. Gastrointest Endosc. 2006 Apr;63(4):570-580.

Ho MY, Blanke CD. Gastrointestinal Stromal Tumors: Disease and Treatment Update. Gastroenterology. 2011;40:1372-1376.

Khushalani NI. Cancer of the Esophagus and Stomach. Mayo Clin Proc. 2008;83(6):712-722.