Early gastric cancer with malignant invasion into the duodenum: A case report.

[RATIONALE] Well-differentiated early gastric cancer (EGC) typically exhibits limited invasive potential, and duodenal involvement is exceedingly rare. This report presents a unique case of a well-differentiated early gastric cancer with extensive duodenal invasion. Magnifying endoscopy is critical for elucidating the growth and infiltration patterns of such lesions. Furthermore, this study provides a detailed magnified endoscopic comparison between the gastric and duodenal mucosa.

[PATIENT CONCERNS] A 62-year-old female patient presented with 20 days of epigastric discomfort, but no nausea, vomiting or difficulty eating. Gastroscopy was performed to clarify the diagnosis, revealing circumferential thickening of the distal gastric sinus that continued across the pylorus to the duodenum. The patient was subsequently hospitalized for further endoscopic examination and pathological biopsy, and was diagnosed with early differentiated gastric cancer that had invaded the duodenum.

[DIAGNOSES] Early gastric cancer with duodenum invasion.

[INTERVENTIONS] laparoscopic-assisted major gastrectomy with Billroth II anastomosis and D2 lymph node dissection.

[OUTCOMES] The patient underwent successful surgery and was discharged after 9 days of postoperative rehabilitation.

[LESSONS] This case provides evidence to support the idea that early gastric cancer can spread to the duodenum by directly penetrating the pylorus. It also presents magnified endoscopic images and histopathological analyses that have not been shown in previous reports.