Synchronous Duodenal Adenocarcinoma and Colon Adenoma Following with Lynch Syndrome Requiring Pancreaticoduodenectomy and Completion Total Colectomy with Ileorectal Anastomosis.

Background: A 59-year-old woman with strong family history of early-age colorectal cancer was found to have synchronous tubular adenomas of the duodenum and transverse colon during surveillance endoscopy 12 years after undergoing right colectomy and adjuvant chemotherapy for stage II colon adenocarcinoma. The duodenal lesion was endoscopically unresectable due to central depression, and the transverse colon adenoma was unresectable because it was confluent with the previous ileocolic anastomosis. Given the synchronous unresectable lesions in the setting of an Amsterdam positive kindred, the patient underwent simultaneous pancreaticoduodenectomy and completion total abdominal colectomy with ileorectal anastomosis. Histopathologic analysis of the specimens revealed T4N0 poorly differentiated MLH1 deficient duodenal adenocarcinoma with pancreatic invasion and tubular adenoma of the colon with high grade dysplasia. Following adjuvant chemotherapy, there is no evidence of recurrent cancer after two years of surveillance.

Summary: While the crude overall risk for small bowel and periampullary tumors remains low, clinicians must maintain awareness of a relatively increased risk of extracolonic tumors in Lynch syndrome (LS) patients.

Conclusion: LS patients have an increased risk for developing small bowel cancer (SBC) when compared to the general population. However, given the low incidence of these tumors and uncertain efficacy of contemporary screening modalities, surveillance of the small bowel has not been recommended. The current case report exemplifies the challenges associated with waiting for patients to develop symptoms to develop before investigating for SBC.