Gastric adenomatous polyp is a premalignant epithelial neoplasm arising from the gastric mucosa, accounting for 6-10% of all gastric polyps. It may display tubular, villous, or tubulovillous histological patterns. Most commonly found in the antrum, presenting as sessile or short-pedunculated, lobulated surface polyp. It contains dysplasia with adenocarcinoma development risk of 6-47% — risk increases with size (>2 cm), proportion of villous component, and presence of high-grade dysplasia. Gastric adenomatous polyps occur with increased frequency in familial adenomatous polyposis (FAP) and Gardner syndrome. On CT, it appears as an antral mucosal polypoid mass with enhancement. Endoscopic polypectomy may be curative; however, surgical resection is required in the presence of high-grade dysplasia or invasive carcinoma.
Age Range
45-80
Peak Age
65
Gender
Male predominant
Prevalence
Uncommon
Gastric adenomatous polyp arises from dysplastic transformation of normal gastric mucosal epithelium — the gastric version of the adenoma-carcinoma sequence. At the molecular level, Wnt/beta-catenin signaling pathway activation, APC gene mutation (especially in FAP), p53 mutation, and microsatellite instability play roles in pathogenesis. Adenomas developing on intestinal metaplasia background carry particularly high malignancy risk — the Correa hypothesis explaining Helicobacter pylori-driven chronic inflammation → atrophic gastritis → intestinal metaplasia → dysplasia → carcinoma cascade describes this process. Adenomatous polyps result from uncontrolled proliferation of mucosal glandular structures; dysplastic cells lose normal glandular differentiation and show nuclear atypia and increased mitotic activity. Enhancement on CT derives from neovascular capillary network within the polyp — dysplastic epithelium stimulates angiogenesis through VEGF expression. The correlation between size increase and invasive carcinoma risk results from increased genetic instability in larger polyps and selection of invasive clones.
Lobulated (cauliflower-like) surface enhancing mucosal polypoid mass in the gastric antrum — suggestive finding for adenomatous polyp. Distinguished from smooth-surfaced hyperplastic polyps by presence of lobulation.
In CT arterial phase, a mucosal-origin, lobulated-surface, moderately to prominently enhancing polypoid mass is observed in the gastric antrum. Enhancement is more prominent than surrounding normal mucosa — reflecting neovascular structure. May be broad-based (sessile) or short-pedunculated.
Report Sentence
A [size] mm lobulated-surface, enhancing mucosal polypoid mass in the gastric antrum is identified, consistent with adenomatous polyp.
In portal venous phase, the polyp maintains enhancement. Central low-density area in large polyps (>2 cm) suggests necrosis or cystic degeneration and increases malignancy risk.
Report Sentence
In portal venous phase, the polyp maintains enhancement [with/without central low-density area].
On EUS, a hyperechoic or intermediate echogenicity, lobulated surface polypoid lesion originating from mucosal/submucosal layer is observed. Muscularis propria is intact — no invasion. Internal echo pattern may be homogeneous or mildly heterogeneous.
Report Sentence
On EUS, a [size] mm mucosal-origin, lobulated polypoid lesion in the gastric antrum with intact muscularis propria is identified.
On non-contrast CT, a mucosal polypoid lesion of soft tissue density (30-50 HU) is observed. Best evaluated when gastric lumen is filled with fluid. Detection becomes difficult for small polyps (<1 cm).
Report Sentence
On non-contrast CT, a [size] mm soft tissue density mucosal polypoid lesion in the gastric antrum is identified.
On T2-weighted sequences, the polyp shows intermediate signal intensity. Villous component may appear more hyperintense due to high water content. Lobulated surface morphology may also be visible on T2.
Report Sentence
On MRI T2-weighted sequence, the polyp demonstrates intermediate signal intensity with visible lobulated surface morphology.
On DWI, adenomatous polyp may show mild-to-moderate diffusion restriction — reflecting increased cellularity of dysplastic cells. Diffusion restriction is more prominent with high-grade dysplasia. ADC values tend to be lower than benign polyps.
Report Sentence
On DWI, the polyp demonstrates [mild/moderate] diffusion restriction with signal decrease on ADC map.
Criteria
Villous component <25%. Most common type, low malignancy risk.
Distinct Features
Smaller size, regular glandular architecture, low-grade dysplasia predominant.
Criteria
Villous component >75%. Higher malignancy risk (up to 40%).
Distinct Features
Larger size, papillary projections, carpet-like growth pattern. More hyperintense on T2 MRI (mucin content).
Criteria
Villous component 25-75%. Malignancy risk intermediate between two types.
Distinct Features
Mixed histology. Mixed pattern of tubular and villous areas on imaging.
Criteria
Multiple gastric adenomas in familial adenomatous polyposis background. APC gene mutation positive.
Distinct Features
Multiple polyps with colonic polyposis. Requires increased surveillance. Duodenal adenomas may also coexist.
Distinguishing Feature
Hyperplastic polyp smooth-surfaced, smaller, no dysplasia; adenomatous polyp lobulated surface, larger, contains dysplasia
Distinguishing Feature
Carcinoma wall thickening, serosal invasion, LAP; adenomatous polyp mucosal-confined, muscularis propria intact
Distinguishing Feature
GIST submucosal/muscularis propria origin; adenomatous polyp mucosal origin — layer difference on EUS
Distinguishing Feature
Carcinoid submucosal, more prominent arterial enhancement, chromogranin positive; adenomatous polyp mucosal origin, contains dysplasia
Urgency
urgentManagement
surgicalBiopsy
NeededFollow-up
6-monthAdenomatous polyp is a premalignant lesion requiring mandatory biopsy and histopathological evaluation. Complete excision via endoscopic polypectomy may be curative, but surgical gastrectomy may be required if high-grade dysplasia or invasive carcinoma is detected on histology. Invasive carcinoma probability is 30-47% in >2 cm polyps. Regular endoscopic surveillance is mandatory in FAP patients. Endoscopic follow-up at 6-12 month intervals is recommended post-polypectomy.
Adenomatous polyps are considered premalignant. All adenomatous polyps should be removed by endoscopic polypectomy. Polyps >2 cm have high dysplasia risk. Surveillance endoscopy after polypectomy is recommended.