Objectives: Juvenile polyps involving the stomach are uncommon. Massive gastric juvenile polyposis is even rarer.
Methods: We describe the clinicopathologic features of nine cases of massive gastric juvenile polyposis.
Results: All patients had anemia; four had hypoalbuminemia. The polyps were composed predominantly of dilated crypts lined by columnar epithelium and abundant edematous stroma with mixed inflammatory infiltrates. One patient had a poorly differentiated adenocarcinoma, arising in juvenile polyp-associated intraepithelial neoplasia. A second patient had a well-differentiated intramucosal adenocarcinoma arising in a juvenile polyp with high-grade dysplasia. Three of our cases had polyposis restricted to the stomach. Six (66.6%) had loss of SMAD4 immunoreactivity, making them subject to severe bleeding and hypoproteinemia, as well as developing severe dysplasia or adenocarcinoma.
Conclusions: SMAD4 immunohistochemstry is a helpful ancillary diagnostic test in cases of suspected juvenile polyposis syndrome involving the stomach.
Keywords: Immunohistochemistry; Juvenile polyps; Massive gastric juvenile polyposis; SMAD4.
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