Small intestinal adenocarcinoma accompanied by lynch syndrome: A case report.

RATIONALE: Lynch syndrome is caused by germline mutations of DNA mismatch repair genes. A significant risk increase for several types of cancer is one of the characteristics of lynch syndrome.

PATIENT CONCERNS: A 45-year-old female presented to the emergency department with abdominal pain that had persisted for a month.

DIAGNOSES: The abdominal and pelvic computed tomography scan showed edematous and thickening of the proximal small bowel wall, as well as dilatation of the proximal bowel and stomach.

INTERVENTIONS: Tumor resection of the small bowel was performed, and adenocarcinoma was confirmed pathologically. Microsatellite instability was also confirmed.

OUTCOMES: Postoperative imaging revealed soft tissue lesions with potential for tumor seeding. Two months after the first surgery, a secondary surgery was performed as a result of cancer recurrence. The patient received chemotherapy with capecitabine. The latest computed tomography scan, performed 19 months after the cessation of chemotherapy, did not show any recurrence.

LESSONS: In the rare incidence of small bowel cancer genetic mutation testing and detailed family history should be actively considered.