Polyps

— hyperplastic: usual type, often antral and regenerative in nature. A 1-3% risk of malignancy* particularly if large (>2cm) and multiple.

*Either within the polyp or elsewhere in the stomach.

— fundic gland cyst: very common. Association with colorectal pathology of various types (rare), familial adenomatous polyposis coli (FAPC) and proton pump inhibitor therapy (due to parietal cell hyperplasia secondary to hypergastrinaemia). Rarely dysplastic (FAPC).

— adenomatous: 8% of cases with a 30-40% risk of malignancy* related to size (>2cm), villous architecture and grade of dysplasia.

— rare: FAPC, Peutz-Jeghers, Cowden's syndromes.

Menetrier's disease and lymphocytic gastritis: hyperplastic gastropathy can be associated with adenocarcinoma.

Synchronous gastric lymphoma of mucosa associated lymphoid tissue (MALToma): also Helicobacter related.

Tumours covered by intact mucosa, such as diffuse gastric carcinoma (signet ring cell) or stromal tumours, can be difficult to demonstrate by routine biopsy and multiple biopsies with jumbo forceps may be required. Cytological brushings and washings or endoscopic fine-needle aspiration cytology may be helpful. In general, gastrointestinal cytology may yield positive information in the following situations:

a. FNA of submucosal/mural/extrinsic lesions including enlarged locore-gional lymph nodes found on staging CT/ELUS

b. FNA of pancreatic mass lesions and brushings of common bile duct/pancreatic duct strictures c. brush cytology of oesophageal and colonic strictures not amenable to usual biopsy.

Multiple (5 or 6) biopsies should be taken from ulcerated carcinomas including the ulcer base and mucosal edges. Distinction must be drawn between carcinoma and pseudomalignant changes in glandular epithelium, endothelial cells and stromal cells in erosions and ulcer base tissue. Biopsy from the base of a deeply penetrating benign peptic ulcer may yield hepatocytes or pancreatic acinar cells not to be misinterpreted as gastric adenocarcinoma. Gastric xanthoma (CD68 positive, cytokeratin and mucin negative) can also mimic diffuse gastric carcinoma and immuno markers are helpful in these situations.

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