Abstract: Objective:To investigate the computed tomography (CT) features of gastric neuroendocrine neoplasm (GNEN).
Methods:The retrospective and descriptive method was conducted. The clinicopathological data of 30 GNEN patients who were admitted to two domestic medical centers (13 cases in Wenzhou Hospital of Traditional Chinese Medicine and 17 cases in Wenzhou People′s Hospital) from January 2010 to December 2018 were collected. There were 23 males and 7 females, aged (62±4)years, with a range from 27 to 78 years. The patients underwent abdominal CT plain scan and dynamic enhancement scan. Two associate chief radiologists with more than 20 years of work experience observed and analyzed all the images respectively. Observation indicators: (1) CT examination; (2) treatment and postoperative pathological examination; (3) follow-up. Follow-up was conducted using outpatient examination and telephone interview to detect the survival of patients up to December 2018. Measurement data with normal distribution were represented as Mean±SD. Measurement data with skewed distribution were described as M (range).
Results:(1) CT examination: of the 30 patients, 14 had the tumor located in the fundus of stomach, 10 had the the tumor located in the body of stomach, and 6 had the tumor located in the antrum. The tumor was elliptical in 18 cases and irregular in 12 cases. There were 15 cases of endogenous type, 13 cases of exogenous type, and 2 cases of intramural type. Patients with G1 neuroendocrine tumor had the maximum diameter of (6.8±1.6)cm, of which 4 cases had the maximum diameter less than 5.0 cm and 4 cases had the maximum diameter of 5.0 to 10.0 cm. Patients with G2 neuroendocrine tumor had the maximum diameter of (8.3±2.7)cm, of which 1 case had the maximum diameter less than 5.0 cm, 4 cases had the maximum diameter of 5.0 to 10.0 cm, and 2 cases had the maximum diameter greater than 10.0 cm. Patients with G3 neuroendocrine carcinoma had the maximum diameter of (17.8±2.2)cm, of which 6 cases had the maximum diameter of 5.0 to 10.0 cm and 9 cases had the maximum diameter more than 10.0 cm. The tumor showed swelling growth in 14 cases and invasive growth in 16 cases. The tumor boundary was clear in 14 cases and unclear in 16 cases. CT plain scan showed homogeneous tumor density in 10 cases and heterogeneous density in 20 cases. Nine patients had iso-density in the tumor parenchymal part, and the CT value was (34.0±3.5)HU. In the 18 cases of low density, the CT value was (16.6±1.4)HU. In the 3 cases of high density, the CT value was (45.3±3.6)HU. Of the 30 patients, 21 cases had small punctate or small round necrotic cyst lesions in the tumor, 10 cases had mesenteric lymph node, peritoneum, liver metastasis and adjacent omentum invasion; 17 cases had abdominal effusion. In the CT enhancement examination, 12 cases showed mild enhancement, and the CT value was (56.5±6.3)HU; 15 cases showed moderate enhancement, and the CT value was (66.0± 5.4)HU; 3 cases showed significant enhancement, and the CT value was (76.6±5.8)HU. Seven cases showed homogeneous enhancement and 23 cases had heterogeneous enhancement. There were 8 cases with tortuous vessels. (2) Treatment and postoperative pathological examination: of the 30 patients, 10 cases with mesenteric lymph nodes, peritoneum, liver metastasis and adjacent omentum invasion underwent radical total gastrectomy; 14 cases without surrounding tissue invasion or metastasis underwent radical subtotal gastrectomy; 6 cases with tumor diameter less than 4.0 cm and without surrounding tissue invasion or metastasis underwent endoscopic resection. All the 30 patients were confirmed GNEN by postoperative pathological examination, including 8 cases of G1 neuroendocrine tumor, 7 cases of G2 neuroendocrine tumor, and 15 cases of G3 neuroendocrine carcinoma. Results of immunohistochemical staining showed that 30 patients were positive for synaptophysin, 23 were positive for chromogranin A, and 9 were positive for cytokeratin. (3) Follow-up: all the 30 patients were followed up for 10-80 months, with a median follow-up time of 39 months. The 5-year survival rate of 30 patients was 43.3% (13/30). The 5-year survival rates were 6/8, 3/7 and 4/15 of patients with G1 neuroendocrine tumor, G2 neuroendocrine carcinoma, and G3 neuroendocrine carcinoma.
Conclusions:GNEN has the main manifestation as abdominal pain, with G3 as pathological classification, which is common in fundus and body of stomach. The CT findings of GNEN are characterized by swelling or infiltrating growth and round or irregular low-density masses. Tumors are prone to cystic transformation, and showed the mildly to moderately heterogeneous enhancement.