[Serrated adenomas of the colon: Clinical, morphological, and molecular genetic characteristics]

[Comparative assessment of the expression of Muc 2, Muc 5AC, and Muc 6 in serrated neoplasms of the colon]

In the course of the serrated pathway of carcinogenesis, there are changes in the expression of mucins with a characteristic immunophenotypic sign, such as a late loss of intestinal differentiation and an increase in gastric differentiation.

OBJECTIVE

To comparatively assess the expression of Muc 2, Muc 5AC, and Muc 6 in hyperplastic polyps (HPs), sessile serrated adenomas (SSAs) and traditional serrated adenomas (TSAs) of the colon for determination of their role in differential diagnosis.

MATERIAL AND METHODS

Sixty-five serrated masses from 52 patients were examined. Among them, there were 26 SSAs, 26 HPs, and 13 TSAs. A histological examination was done using hematoxylin and eosin staining; periodic acid-Schiff reaction in combination with alcian blue, as well as immunohistochemistry with anti-Muc 2, anti-Muc 5AC, and anti-Muc 6 antibodies were used. Genetic testing of the specimens for KRAS and BRAF mutations was also carried out.

RESULTS

All the serrated neoplasms of the colon exhibited a pronounced expression of Muc 2. A marked Muc 6 expression in the dilated crypt bases was found in 76.9% of SSAs, while no reaction was seen in 92.3% of HPs and in 100% of TSAs. SSAs were characterized by an intense Muc 5AC expression in the whole length of the crypts and in the surface epithelium in contrast with HPs and TSAs, where the expression of the marker was focal. Comparison of the response of the markers and the presence of gene mutations identified that the SSAs with BRAF mutation intensely expressed along the length of the crypt for Muc 5AC and Muc 6; and the TSAs with KRAS mutation had a moderate focal Muc 5AC expression in the crypt bases in 100% of cases.

CONCLUSION

For differential diagnosis of the types of serrated adenomas of the colon, it is useful for a pathologist to apply the immunohistochemical markers Muc 2, Muc 5AC, and Muc 6 in his/her practice.

[Coexpression of CD44 and Ki-67 in colon`s neoplast]

AIM

the evaluation of Ki-67 and CD44 expression in the 'serrated' polyps of the colon and comparison them with adenocarcinomas and tubular and tubule-villous adenomas of the colon.

MATERIAL AND METHODS

The study is including 49 'serrated' polyps, 34 tubular (AT) and tubulo-villous (ATV) adenomas and 32 adenocarcinomas of the colon. Antibodies CD44 and Ki-67 were used as immunohistochemical markers in this study.

RESULTS

A statistically significant difference (p<0.01) was observed between traditional serrated adenomas (TSA) from hyperplastic polyps (HP) and sessile serrated adenomas (SSA) in the Ki-67 level and the localization of the Ki-67 and CD44 reaction: surface areas of the crypts (upper third) in TSA and base of crypts (lower third) in HP and SSA. There was no difference between HP and SSA (p>0.05), neither by marker localization, nor by their level. In all 'serrated' polyps of the colon, the Ki-67 reaction was nuclear; CD44 - membrane (except for 1 TSA).

CONCLUSION

we are the first ones who suggested to evaluate not the overall level of reactions of CD44 and Ki-67, but particular level for each third part of crypts. The similarities of TSA, AT and ATV and between HP and SSA are shown as well as the principal statistical difference between these two groups. The cytoplasmic reaction of CD44 in adenocarcinomas and the membrane reaction of CD44 in 98% of the 'serrated' polyps of the colon are described. For the first time coexpression of CD44 and Ki-67 on particulate thirds of crypts in neoplasms of the colon is shown and the potential reasons for this phenomenon are discussed.