SPORADIC FUNDIC GLAND POLYPS - AN IMMUNOHISTOCHEMICAL STUDY OF THEIR ANTIGENIC PROFILE

Fundic Gland Polyps (FGPs) are small sessile (2-5 mm), usually multipl e polyps arising in the gastric, acid-secreting mucosa of disputed his togenesis. They have been described in a sporadic form, prevalently in middle aged females, or associated with familial adenomatosis coli-Ga rdner's syndrome. We performed an immunohistochemical study on 24 spor adic FGPs, using monoclonal antibodies (MAbs) against differentiation markers, class II MHC antigens (HLA-DR), oncofetal and proliferation a ntigens, aimed to characterize the antigenic profile of the polyps. A preliminary cytogenetic study on five polyps was also done, using an i n situ culture method after collagenase treatment. Cytokeratins 8-18 ( CAM 5.2 MAb) and 20 (IT-Ks 20.8 MAb), Epithelial Membrane Antigen (EMA ) and Chromogranin A were normally expressed by FGPs. FGPs did not exp ress HLA II DR. FGPs did not react with an anti-CEA MAb (F6), but they were frequently positive (22/24, 91.6%) with B72.3 MAb (reacting with the cancer-associated mucin epitope sialyl-Tn). The PC10 MAb (against PCNA or cyclin) showed enhanced expression in the deep glandular-cyst ic compartment of FGPs; the PCNA index of FGPs was significantly highe r than in normal fundic mucosa. The cytogenetic study on the 5 cases a nalysed, revealed a normal karyotype. We have demonstrated that FGPs e xpress in the paranuclear zone the sialyl-Tn epitope, a side-chain sug ar normally masqued in adult gastric mucins, thus revealing an alterat ion in mucin synthesis; FGPs' higher proliferation index as compared w ith normal fundic mucosa supports the hypothesis of their hyperprolife rative nature.