[Value of detection of DNA mismatch repair proteins deficiency by immunohistochemistry in predicting XXXX microsatellite status].

@entity124 @entity5 @entity4311 @entity14437 @entity14 @entity4638
OBJECTIVE: To evaluate the sensitivity and specificity of immunohistochemical (IHC) staining of DNA mismatch repair (MMR) protein for the screening of @entity124 ( @entity124 ) @entity14 ( @entity14 ). METHODS: A total of 255 @entity14 cases were studied, including 140 cases of routine paraffin-embedded tissue samples and 115 cases constructed on tissue microarray. Expressions of 4 MMR proteins including MHL1, @entity4311 , @entity4638 and @entity14437 were investigated by IHC. Negative protein expression was defined as complete absence of nuclear staining within @entity5 cells in the presence of positively labeled internal non-neoplastic cells. Focal staining was defined as the presence of staining in < 5% of the @entity5 cells. CRCs showing negative staining for any MMR proteins were interpreted as MMR deficient @entity5 . PCR-genescan @entity124 analysis was performed in each case by a five marker panel including Bat26, Bat25, NR-21, NR-24 and MONO-27. RESULTS: Among the 140 CRCs with routine formalin-fixed paraffin embedded tissue sections, concordance rate between IHC and PCR-genescan was 98.6% (138/140), the sensitivity and specificity of IHC in detecting @entity5 were 94.9% (37/39) and 100.0% (101/101), respectively. The 2 disconcordant cases showed focal staining in at least one of the MMR proteins but were confirmed to be @entity124 CRCs by PCR-genescan assay. On tissue microarray, 91.3% (105/115) of the cases had informative results. The concordance rate between IHC and PCR-genescan was 100.0% (105/105). Both the specificity and sensitivity of IHC in detecting @entity5 on available tissue microarray samples were 100.0%. Ten cases were inclusive due to the presence of negative stains of MMR proteins in both the @entity5 and internal control cells. CONCLUSIONS: Detection of 4 MMR proteins expression by IHC is reliable for identifying @entity124 CRCs and is recommended for routine practice. @entity5 with focal MMR protein staining are highly suspected for the presence of @entity124 and PCR-genescan based @entity124 analysis should be performed to confirm.
