Objective:To investigate the clinicopathological characteristics, treatment methods and prognosis of renal primary neuroendocrine neoplasms.Methods:The clinical data of 42 patients with renal neuroendocrine neoplasms admitted to the First Affiliated Hospital of Zhengzhou University from October 2011 to June 2021 were retrospectively analyzed.There were 17 males and 25 females. The median age was 60.0 (50.0, 67.0) years old.The CT enhancement scan lesion was slightly intensified with less intensification than normal renal parenchyma.The clinic manifestation included lumbar abdominal pain in 7 cases, hematuria in 3 cases, abdominal distension in 1 cases, and asymptomatic in 8 cases. The average diameter of tumor was 8.0 (4.0, 10.0) cm. The tumor of 13 cases was in the left, and 6 cases was in the right. 6 cases were in T 1 stage, 11 cases were in T 2, 11 cases were in T 3, and 14 cases were in T 4.17 cases had lymph node metastasis, 11 cases had distant metastasis.The surgical method was radical nephrectomy in 27 cases, nephrectomy in 5 cases and interventional embolization in 4 case, and no operation in 6 cases, including 5 with chemotherapy alone and 1 with supportive care.Patients were classified by WHO Classification of renal tumors of the urinary system and the male reproductive organs (2016) into high-differentiated renal neuroendocrine tumors (NET, including carcinoid and atypical carcinoids) and high-grade renal neuroendocrine carcinoma (NEC, including small cell neuroendocrine carcinoma and large cell neuroendocrine carcinoma). The clinicopathological characteristics and prognosis of the 2 groups were compared, and the Cox proportional regression risk model was used to analyze the clinical factors affecting the prognosis. Results:In the NET group, 12 cases were carcinoids and 7 cases were atypical carcinoids. In the NEC group, 23 cases were small cell carcinomas.The mean Ki-67 index of 42 cases was 35% (4.5%, 62.5%). The proportion of positive expression of the neuroendocrine markers CD56, chromogranin A (CgA), and synapsin (Syn) were (37/42), (15/42), and (38/42), respectively. A total of 42 patients were followed up, and the median follow-up time was 60 (35, 99) months, and the median survival time was 25 (15, 60) months. The 3-year and 5-year overall survival rates were 40.0% and 21.2%. The 3-year and 5-year overall survival rates in the NET group were 72.6% and 42.3%.The 3-year and 5-year overall survival rates in the NEC groups were 6.3% and 0, respectively. The mean Ki-67 index was 3% (2%, 10%) in the NET group, 2 patients received postoperative chemotherapy and 3 patients had early progression after initial treatment.The mean Ki-67 index in the NEC group was 60% (40%, 80%), 15 patients received postoperative chemotherapy, and 13 patients had early progression of initial treatment.There were statistically differences in treatment method, postoperative chemotherapy, Ki-67 index, and early disease progression (all P <0.05) between the two groups.The results of univariate analysis showed that sex, age, early progression, treatment method, tumor differentiation, and Ki-67 index were all factors influencing patient prognosis (all P <0.05). Cox multivariate analysis showed that poorly differentiated NEC ( HR=13.964, P=0.003) and early progression ( HR=3.626, P=0.018) were independent risk factors for patient survival, and renal radical surgery ( HR=0.197, P=0.033) was independent protective factors for patient survival. Further subgroup analysis showed that the median survival time of the NEC patients with adjuvant chemotherapy after surgery was significantly longer compared with the patients without adjuvant chemotherapy (21 and 9 months, P=0.012). Conclusions:Primary renal neuroendocrine tumors are clinically rare, often manifested as lumbar and abdominal pain, and radical renal surgical treatment is preferred.The NET has a better prognosis and NEC prognosis is extremely poor, but NEC patients can have survival benefit from chemotherapy. NEC and early progression of the disease are independent prognostic risk factors, and radical renal surgical treatment is an independent protective factor for prognosis.