Mismatch repair gone awry: Management of Lynch syndrome

• Lynch syndrome patients have mutations in genes necessary for DNA mismatch repair.
• Pathologic testing for MSI includes IHC or PCR testing for specific mutations.
• In the CAPP2 trial, aspirin protects against colorectal cancer in Lynch syndrome.
• Surveillance colonoscopies every 1–2 years improve colorectal cancer detection.

The hallmark of Lynch syndrome involves germline mutations of genes important in DNA mismatch repair. Affected family kindreds will have multiple associated malignancies, the most common of which is colorectal adenocarcinoma. Recently, evidence has shown that clinical diagnostic criteria provided by the Amsterdam Criteria and the Bethesda Guidelines must be linked with microsatellite instability testing to correctly diagnose Lynch syndrome. We present a case of metachronous colorectal adenocarcinomas in a patient less than 50 years of age, followed by a discussion of Lynch syndrome, with an emphasis on surveillance and prevention of malignancies.