A woman in her 80s underwent surgery for ascending colon cancer about four years ago; she had a positive surgical margin. However, chemotherapy was not given according to the patient's wish. Abdominal computed tomography three years after surgery revealed a mass lesion in the descending part of the duodenum. A submucosal (mesenchymal) tumor was suspected on endoscopic ultrasonography. However, endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) cytology revealed adenocarcinoma, with findings similar to pathological findings at the time of surgery four years earlier. The patient was therefore diagnosed with a duodenal recurrence of her prior ascending colon cancer. EUS-FNA is minimally invasive and is useful for the diagnosis of tumor-like lesions in the submucosa.
