Clinical Challenges

What's your diagnosis?

Publish date: June 1, 2023
By
Jad Abimansour, MD
Tsung-Teh Wu, MD
Seth Sweetser, MD

A 72-year-old man with compensated cirrhosis owing to autoimmune hepatitis presented for evaluation of an indeterminate gastric lesion found during an otherwise normal endoscopic retrograde cholangiopancreatography performed for incidental ductal dilation seen on cross-sectional imaging. He did not endorse any abdominal pain, dyspepsia, or weight loss and was not on a proton pump inhibitor. Family history was notable for a daughter diagnosed with metastatic gastric adenocarcinoma at the age of 44 years.


Upper endoscopy showed innumerable sessile polyps of variable size carpeting the gastric body and fundus (Figure A) with a large, mound-like mass lesion in the fundus (Figure A, arrow and inset). Echoendoscopy revealed a hypoechoic, noncircumferential mass restricted to the mucosal surface with well-defined borders (Figure B, arrow). A technically challenging, piecemeal endoscopic mucosal resection was performed. The patient also underwent a colonoscopy that was unremarkable. Pathology of the gastric lesion was consistent with a fundic gland polyp (Figure C, arrowheads) containing low-grade and high-grade dysplasia (Figure C, arrows).

What is the most likely diagnosis?


 

Answer to ‘What’s your diagnosis?’: Gastric adenocarcinoma and proximal polyposis of the stomach syndrome.

Fundic gland polyps (FGPs) are the most common gastric polyps and when occurring in the sporadic setting are typically benign; however, FGPs that occur in gastrointestinal polyposis syndromes such as familial adenomatosis polyposis can progress to adenocarcinoma and require surveillance. Therefore, it is important to distinguish sporadic versus syndromic fundic gland polyposis. Gastric adenocarcinoma and proximal polyposis of the stomach is a recently described condition that significantly increases the risk of developing invasive gastric adenocarcinoma from FGPs. Diagnostic criteria include (1) gastric polyposis restricted to the body and fundus with no small bowel or colonic involvement, (2) >100 gastric polyps or >30 polyps in a first-degree relative, (3) histology consistent with FGP with areas of dysplasia, (4) a family history consistent with an autosomal-dominant pattern of inheritance, and (5) exclusion of other syndromes and proton pump inhibitor use.1 Unlike familial adenomatosis polyposis, the polyposis is restricted to the oxyntic mucosa of the gastric body and fundus with sparing of the gastric antrum, small bowel, and colon. The genetic basis of the disease has been attributed to a point mutation in the APC gene promotor IB region leading to a loss of tumor suppressor function.2 Typical histology shows large FGPs with areas of low-grade and high-grade dysplasia, as seen in our patient.

There are few data on the natural history of gastric adenocarcinoma and proximal polyposis of the stomach, but effective surveillance is limited by the degree of polyposis. There are multiple reports of hidden adenocarcinoma on surgically resected specimens, as well as rapid progression to metastatic adenocarcinoma despite adequate diagnosis and surveillance.1,3 Therefore, total gastrectomy should be offered to patients who are surgical candidates. Our patient underwent genetic testing that revealed a point mutation in the APC promotor IB. He declined surgical intervention and opted for surveillance endoscopy every 6 months.

References

1. Worthley D.L. et al. Gut. 2012;61:774-9

2. Li J et al. Am J Hum Genet. 2016;98:830-42

3. Rudloff U. Clin Exp Gastroenterol. 2018;11:447-59

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