[Gastric adenocarcinoma arising in giant hyperplastic polyp]

Gastric hyperplastic polyps are usually solitary, their development is supposed to be associated with excessive proliferation of foveolar cells. It is essential to differentiate hyperplastic polyps from other sporadic polyps (adenomatous and fundic gland polyps) and lesions, included in familial polyposis syndromes. The frequency of adenocarcinoma in large gastric hyperplastic polyps (more than 1-2 cm in size) is about 2,1%. This article includes case report of gastric adenocarcinoma arised in large hyperplastic polyp in a 56-year-old patient. On histological examination a well-differentiated adenocarcinoma without invasion in the peduncle was identified. Immunohistochemically cells of adenocarcinoma showed elevated expression of claudin-3, CDX2, p53 and Ki67 compared to hyperplastic glands and dysplastic areas of the polyp. Also focal expression of MUC2 was revealed in adenocarcinoma. Expression of MUC5AC, CD44 and cyclin D1 was less prominent in cancer areas compared to hyperplastic and dysplastic glands. Levels of expression of claudin-1, claudin-4 and β-catenin were equal in adenocarcinoma and hyperplastic structures. Control endoscopic examination with following morphologic examination was performed three months after surgical operation. No signs of tumor growth were identified.