Small bowel adenocarcinoma in Lynch syndrome: A case report.

Small bowel adenocarcinoma is part of the tumor spectrum of Lynch syndrome, which is caused by germline mutations in the mismatch repair genes. The present study describes the case of a 51-year-old man fulfilling the Amsterdam II criteria for Lynch syndrome, who had a 15-mm early-stage colorectal cancer resected endoscopically from the ascending colon. Due to upper abdominal discomfort after eating and consequent anorexia, a computed tomography scan performed 1 month later showed a tumoral mass of the upper jejunum with local lymphadenopathy. The laparotomy revealed a completely obstructing mass. Intraoperative frozen section showed a small bowel adenocarcinoma. Subsequent genetic testing confirmed the germline mutation of mutL homolog 1. The patient received 6 cycles of an adjuvant folinic acid, fluorouracil and ocaliplatin chemotherapy regimen. The latest CT scan, 16 months after the chemotherapy, did not show any recurrence. This case highlights the importance of considering the possibility of small bowel adenocarcinoma in patients with upper bowel obstruction, particularly for patients with Lynch syndrome.