MRC1 and Lynch syndrome: A previous study from our institution showed that a normal IHC test for MLH1 and MSH2 has a 96.7% positive predictive value for a microsatellite stable/MSI-L phenotype.9 On the basis of the IHC data alone, it is highly unlikely that the patient has a germline mutation in an MMR gene, which would lead to Lynch syndrome with MSI.9