Gastric Collision Tumor (Adenocarcinoma and Neuroendocrine carcinoma) Diagnosed as a Advanced Gastric Cancer

ABSTRACT

The collision tumors have been reported in various organs and represent the coexistence of two adjacent but histologically distinct tumors in an organ without any histological admixture. A gastric collision tumor is rare and most gastric collision tumors involve an adenocarcinoma colliding with a lymphoma. A 48-year-old man was referred to our hospital for an evaluation of dyspepsia and upper abdominal discomfort. Endoscopy demonstrated the presence of an ulcerative lesion in the gastric antrum. The biopsy specimens confirmed a pathological diagnosis of an adenocarcinoma. After a radical subtotal gastrectomy, a thorough Histopathological examination revealed a collision tumor: a well-differentiated adenocarcinoma in the superficial layer (mucosa, submucosa) and a poorly differentiated neuroendocrine carcinoma in the deeper layer (muscularis propria, serosa). The patient received combination chemotherapy with cisplatin and etoposide. Para-aortic lymph node enlargement was observed on the abdominal computed tomography scanning, 3 years after surgery. The patient underwent chemotherapy with TS-1, and the size of lymph nodes was reduced. The patient continues to do well after a follow up period of 5 years 3 months. We report this case of gastric collision tumor (adenocarcinoma and neuroendocrine carcinoma) with a brief review of the relevant literature.