Mixed neuroendocrine carcinoma of the gastric stump: A case report.

BACKGROUND Gastric stump cancer, also known as gastric remnant cancer (GRC), is one of the main complications of postgastrectomy syndrome, which usually occurs following Billroth II reconstruction. The predominant histological subtype of GRC is adenocarcinoma, whereas neuroendocrine carcinoma is relatively rare. In particular, there are few recently reported cases of mixed neuroendocrine carcinoma (MNEC) in the English literature. Here, we present an extremely rare case of MNEC of the gastric stump. CASE SUMMARY A 59-year-old patient presented to our department owing to chronic constipation. He had undergone subtotal gastric resection 35 years prior to admission because of benign peptic ulcer. After admission, the patient underwent several tests, and gastroendoscopy showed evidence of Billroth II gastrectomy and local thickening of the gastric stump mucosa at the gastrojejunostomy site, with bile reflux; pathological biopsy revealed adenocarcinoma. He was then diagnosed with GRC and underwent total gastrectomy, D2 Lymphadenectomy, and esophagojejunal Roux-en-Y reconstruction. Histopathological examination of the specimen identified MNEC comprising MNEC (60%), adenocarcinoma (30%), and squamous cell carcinoma (10%). Postoperative adjuvant chemotherapy was initiated on September 17, 2020. Taxol plus cisplatin was administered for only one cycle because of severe liver function damage, and the regimen was changed to etoposide plus cisplatin on October 10, 2020 for five cycles. The patient recovered, with no recurrence after 6 mo of follow-up. CONCLUSION Gastric MNECs (GMNECs) is a rare type of GRC. This study presented the unusual occurrence of GMNEC in the gastric stump. This case will contribute to improvements in our understanding of the carcinogenesis, biology, pathology, and behavior of GMNEC and GRC.