S1647 A Surprising Diagnosis of Lynch Syndrome at Age 86

Abstract

INTRODUCTION: Lynch syndrome (LS) is the most common inherited colorectal cancer (CRC) syndrome and accounts for up to 6% of all CRCs in the United States. The lifetime risk of CRC is near 75% for individuals with this inheritable highly expressed gene making identification of individuals and at-risk family members important for cancer prevention and management. CASE DESCRIPTION/METHODS: 86-year-old male in excellent physical condition with history of right-sided poorly differentiated invasive stage IIa adenocarcinoma status post right hemicolectomy 12 years ago presented after 6 episodes of painless hematochezia (hemoglobin 11.9 g/dL). He chose not to undergo chemotherapy and never had a follow-up colonoscopy following his initial CRC. He reported a family history of 1 sister who recovered from breast cancer and 2 deceased younger brothers who passed from colon cancer after his original diagnosis of CRC. Both parents experienced early death from cardiovascular disease. He had 6 children. Colonoscopy revealed normal ileocolonic anastomosis but with a 3 cm ulcerated, friable mass in transverse colon, a 2.5 cm mass in rectosigmoid colon, and a large, fungating 4cm ulcerated mass 5 cm from the anal verge. CT chest/abdomen/pelvis scan demonstrated extension of the transverse colonic mass through the colon wall into the mesentery with extensive nodal and hepatic metastatic disease. Pathology revealed invasive moderately differentiated adenocarcinoma positive for MLH1, MHS2, and PMS2 suggestive of Lynch syndrome; absent MSH6 staining was noted. Family members were recommended for genetic testing. The patient ultimately opted against treatment. DISCUSSION: The average age of colon cancer diagnosis for those with LS is 44 as compared to 68 for men without the genetic syndrome. This case demonstrates a particularly unique diagnosis of Lynch syndrome in an elderly male that was not diagnosed until his second bout of CRC. Of note, both cancers occurred after age 70. Strict adherence to the revised Bethesda guidelines can miss 68% of high microsatellite instability CRCs suggesting these guidelines are inadequate for LS screening, particularly if a full multigenerational family cancer history is not available. Multiple studies have demonstrated economic feasibility and advocate for universal LS testing of CRC tumors. This case supports such a paradigm. For identifying those who may be at risk for LS, we would prefer a predictive model without an overreliance on age to determine those appropriate for screening.Figure 1.: Endoscopic view of the 3 cm transverse colon (A), 2.5 cm rectosigmoid colon (B), and 4 cm anal verge (C) masses in an 86-year-old male discovered to have Lynch syndrome.Figure 2.: CT abdomen/pelvis showing transverse colon carcinoma with direct extension through the colon wall (red arrow) and into the mesentery associated with extensive nodal, as well as hepatic (yellow arrows) metastatic disease in an 86-year-old male discovered to have Lynch syndrome.