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Découverte inattendue d'un marquage sur un type de cellule: lequelle?


Discovered upon making an immunohistochemistry : Guess the cell type,

  EMA Moyen grossissement   EMA high power  
  Muqueuse gastrique fundique, Cellules bordantes ou paritales, présentent des canalicules s'etendant dans le cytoplasme (voir cliché en microscopie electronique à droite), et drainant la production d'acide.   Fundic gastric mucosa: Parietal cells:Canaliculi extending throughout the cytoplasm. The canalicular system actively participates to the secretion of hydrochloric acid.  
  Reference:   Acknowledgement to Dr Sameh GEHA  
  Pol J Pathol. 2006;57(3):141-8:  
  Immunophenotype of sporadic and familial adenomatous polyposis associated fundic
gland polyps: a mucin and MIB1 study.

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.

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.