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Declich P, Carneiro F, Omazzi B, Tavani E, Grassini R, Ferrara A, Bortoli A,
Bellone S, Gozzini C, Prada A.
Service of Pathology, Rho Hospital, Italy. paolo.declich@libero.it
BACKGROUND: Fundic Gland Polyps (FGPs) are small sessile (2-5 mm) usually
multiple polyps arising in the gastric, acid-secreting mucosa, described both in
a sporadic form, prevalently in middle aged females, and associated with familial
adenomatosis coli (FAP)-Gardner's syndrome and their attenuated variants
(syndromic form). AIMS: We performed an immunohistochemical study on 5 syndromic
(4 cases without and 1 case with dysplasia) and 28 sporadic FGPs, using
monoclonal antibodies (MoAbs) against normal epitopes of fundic mucosa (Ck20, the
surface gastric mucin M1, EMA, ChA), H. pylori and HLA-DR(Ia) antigens, CEA and
mucin epitopes, and the Ki67 (MIB1) proliferation antigen, in order to establish
the immunophenotype of FGPs; find any possible differences between sporadic and
syndromic polyps. RESULTS: Ck20 and M1 were positive on surface and foveolar
epithelium of controls, whereas sporadic and syndromic FGPs showed an enhanced
deep positivity below foveolar necks ("foveolar metaplasia"); EMA was strongly
positive on parietal cells, highlighting intracytoplasmic canaliculi.
Chromogranin-positive cells in FGPs were alike controls, except for a sporadic
case with micronodular hyperplasia. Ck7, as expected, was negative in controls,
whereas the 5 syndromic FGPs and 25 of 28 sporadic FGPs showed a diffuse
superficial and deep expression. H. pylori anti-serum gave negative results on
all cases, and only 3 sporadic FGPs showed epithelial expression of HLA-DR(Ia).
Syndromic FGPs were CEA negative, whereas 32% of sporadic FGPs expressed it. FGPs
showed a neoexpression of the mucin oncofetal epitopes syalil-Tn (3/5 syndromic,
82% sporadic) CA19.9 and CA50 (4/5 syndromic, 14% sporadic). MIB1-labelling index
of surface (30.5%) and deep (37.1%) compartments of the 4 syndromic FGPs without
dysplasia was enhanced, with high statistical significance (p < 0.0001) both in
comparison to controls (16.9% superficial stain only) and sporadic FGPs (15.8%
surface, 19.5% deep labeling indexes). Moreover, the MIB1 labeling-index of the
syndromic case with dysplasia (60.8% surface, 56.6% deep labeling indexes) was
further enhanced in comparison with the other 2 syndromic cases.
CONCLUSIONS:
Sporadic and syndromic FGPs showed a neoexpression of Ck7, CEA, and mucin
epitopes. As these markers are normal antigens of fetal stomach, FGPs showed a
fetal, "immature" immunophenotype. The only difference we found between syndromic
and sporadic polyps was a statistically significant enhanced MIB1-labelling index
expression by syndromic FGPs, further enhanced in the syndromic FGP with
dysplasia. |
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