Identifying Lynch syndrome: we are all responsible.

PURPOSE: The Amsterdam criteria and Bethesda guidelines are used to identify patients with Lynch syndrome. A family history of Lynch syndrome-related cancers or histopathology suggestive of microsatellite instability should prompt responses by the pathologist and clinician. This study evaluated the impact of microsatellite instability pathology findings on Lynch syndrome evaluation by clinicians.

METHODS: Microsatellite unstable tumors were identified from a maintained tissue bank, and MLH1 methylation was determined. Clinical information and management recommendations by the pathologist and clinician were collected from the medical record.

RESULTS: Fifty-one patients with microsatellite unstable colorectal tumors were identified between 2003 and 2006. Thirteen (25 percent) patients were appropriately referred for additional testing, including eight with documented microsatellite instability histology and five based on history alone. Thirty-seven (73 percent) patients with microsatellite unstable tumors were not detected by pathologists or clinicians, and no additional workup for Lynch syndrome was performed. Two patients met Amsterdam criteria and represent potentially missed Lynch syndrome.

CONCLUSIONS: Microsatellite instability-H histology was the driving force for the Lynch syndrome evaluation. Histopathology alone failed to identify all potential Lynch syndrome patients. Omission of an adequate familial risk assessment may lead to missed diagnosis of Lynch syndrome when suspicious histopathology fails to trigger appropriate testing.