Neuroendocrine Carcinomas of the Stomach: Computed Tomography and Pathologic Findings in 32 Patients

Abstract

Background: Neuroendocrine carcinomas (NECs) of the stomach are poorly differentiated, high-grade endocrine tumors, including small cell and large cell carcinomas. They are deeply invasive and metastatic, with a poor prognosis. The purpose of this study is to describe the computed tomography (CT) findings of gastric NECs with pathologic features. Patients and Methods: CT examinations of 32 patients with gastric NECs from January 2004 to January 2015 were reviewed retrospectively for tumor morphology, size, and CT attenuation. CT attenuation of the lymph nodes, peritumoral infiltration, and associated findings, such as liver metastasis and peritoneal carcinomatosis were also reviewed. The ages of patients ranged from 45 to 79 years (mean: 62 years). Twenty-seven patients (84%) were men. Pathologic diagnosis was made using gastrectomy (n = 28) and endoscopic biopsy (n = 4). Nineteen patients underwent multidetector CT with water as an oral contrast agent, and 13 patients underwent helical CT with water. Results: Among the three CT morphologic types of gastric NEC (polypoid, ulcerofungating, and ulceroinfiltrative), 63% of those in our study were ulcerofungating (n = 20), 37% were ulceroinfiltrative, and none were polypoid. All were larger than 5 cm in the greatest diameter (mean size: 7.8 cm). The characteristic features at presentation were focal (n = 3) or diffuse (n = 15) low attenuation within the mass, extensive low attenuation lymphadenopathy (n = 13), and liver metastasis (n = 6). There were no significant differences between the small cell (n = 10) and the large cell NEC groups (n = 22). Conclusion: Although differential diagnosis between gastric adenocarcinoma and gastric NEC is difficult, gastric NEC should be considered when CT shows a large ulcerofungating tumor with low attenuation areas (pathologically mucinous or necrotic), especially combined with extensive necrotic lymphadenopathy and frequent hepatic metastases.