Characteristics and long-term prognosis of patients with rectal neuroendocrine tumors

Clinical outcomes after endoscopic resection and the risk of lymph node metastasis in rectal neuroendocrine tumors: a single-center retrospective study

BACKGROUND AND AIM

The incidence of rectal neuroendocrine tumors (R-NETs) has increased in recent years. However, the predictors of lymph node (LN) metastasis and clinical outcomes, particularly following endoscopic treatment, remain unclear. Our study aims to elucidate the potential risk factors for LN metastasis and the clinical outcomes of patients undergoing endoscopic resection in R-NETs.

METHODS

A total of 128 patients with R-NETs were retrospectively identified from a single center between June 2012 and December 2021. Risk factors for LN metastasis in R-NETs were analyzed using multivariate analysis. Additionally, the clinical outcomes of endoscopic resections in patients with R-NETs were assessed.

RESULTS

In our study, 128 patients with R-NETs were retrospectively analyzed. The risk factors for LN metastasis determined by multivariate analysis were tumor size and patient age at diagnosis. Among the 111 patients treated with endoscopic resection and with tumor margin records available, 92 underwent endoscopic submucosal dissection (ESD) and 19 underwent conventional endoscopic mucosal resection (EMR). There was no significant difference between the two groups regarding the positive rates of basal tumor margin and lateral tumor margin. Furthermore, 64 patients who underwent endoscopic resection for R-NETs were successfully followed up (range, 1.64-76.71 months), during which only one patient developed local recurrence.

CONCLUSION

Tumor size and age at diagnosis were predictors for LN metastasis of R-NETs. Both ESD and EMR are alternative techniques with a favorable prognosis for R-NETs, even in cases with positive resection margins. However, due to the relatively small number of patients undergoing EMR and missing data in follow-up protocols, definitive conclusions require further large-scale studies.

Assessing the effectiveness and safety of surufatinib versus everolimus or sunitinib in advanced neuroendocrine neoplasms: insights from a real-world, retrospective cohort study using propensity score and inverse probability treatment weighting analysis

Background

While surufatinib, sunitinib, and everolimus have shown efficacy for advanced neuroendocrine neoplasms (NENs) in randomized controlled trials (RCTs), direct comparisons in a real-world setting remain unexplored. This gap highlights the clinical need to understand their comparative effectiveness and safety within the diverse Chinese population. Addressing this, our study provides insights into the real-world performance of these therapies, aiming to inform treatment selection and improve patient outcomes.

Methods

A retrospective, observational study was conducted at Fudan University Shanghai Cancer Center, including patients with advanced NENs treated with surufatinib, sunitinib, or everolimus between July 2020 and April 2023. Eligibility criteria focused on histologically confirmed, locally advanced, unresectable, or metastatic NENs, with patients having received at least one month of targeted therapy. We employed inverse probability weighting (IPW) with the propensity score (PS) matching to adjust for the bias of baseline characteristics. The assessment of covariates included age, sex, performance status, primary tumor site, functional status, genetic mutations, tumor differentiation, Ki67 index, tumor grade, metastasis site, and previous therapies. The primary outcome was progression-free survival (PFS), and secondary outcomes included objective response rate (ORR), disease control rate (DCR), and adverse events (AEs).

Results

The study enrolled 123, 56, and 68 locally advanced or metastatic NEN patients treated with surufatinib, sunitinib, and everolimus, respectively. Before adjusting for confounding factors, surufatinib was used less frequently as a first-line treatment compared to sunitinib and everolimus in pancreatic NENs (pNENs) (11.1% vs. 22.1%, P=0.057). Significant differences were noted in prior treatments and tumor characteristics between surufatinib and everolimus groups in extrapancreatic NENs (epNENs) (P<0.05). Post-IPW, these disparities were resolved (P>0.05). Surufatinib demonstrated superior median PFS (mPFS) in both pancreatic [8.30 vs. 6.33 months, hazard ratio (HR) 0.592, P<0.001] and epNENs (8.73 vs. 3.70 months, HR 0.608, P<0.001) compared to everolimus or sunitinib. Notably, male gender (HR 1.75, P=0.001), functional status (HR 2.09, P=0.01), Ki67 index >20% (HR 12.7, P=0.004), previous somatostatin analogue (SSA) treatment (HR 1.73, P=0.001), germline mutation (HR 5.62, P<0.001), poor differentiation (HR 7.45, P<0.001), liver metastasis (HR 1.72, P=0.001) and multiple treatment lines (HR 1.62 for 2nd line, P=0.04; HR 1.88 for ≥3rd line, P=0.01) were identified as negative prognostic factors for PFS. Conversely, dose adjustment (HR 0.63, P=0.009) and treatment with surufatinib (HR 0.58 for pNEN, P<0.001; HR 0.62 for epNEN, P=0.002) were correlated with longer PFS.

Conclusions

In a real-world Chinese cohort, surufatinib significantly outperformed sunitinib and everolimus in prolonging PFS among advanced NEN patients, with identifiable clinical features impacting survival, and conclusions regarding superiority should be interpreted with caution due to the retrospective design. Our findings underscore the need for prospective studies to further validate these results and explore additional predictive biomarkers for personalized treatment strategies.

Impact of grade on workup of rectal neuroendocrine tumors: a retrospective cohort study : Grade impact on workup of rectal NETs

BACKGROUND

Rectal neuroendocrine tumors (RNETs) are often discovered on screening colonoscopy. Indications for staging and definitive resection are inconsistent in current guidelines. We evaluated the role of grade in guiding staging and procedural decision-making.

METHODS

Patients with biopsy confirmed RNETs between 2004 and 2015 were reviewed. Baseline characteristics, staging investigations (biochemical and imaging), and endoscopic/surgical treatment were recorded. Associations between grade, preoperative staging, interventions, and survival were determined using Fisher-Freeman-Halton Exact, log-rank, and Kaplan-Meier analysis.

RESULTS

Amongst 139 patients with RNETs, 9% were aged ≥ 75 years and 44% female. Tumor grade was: 73% grade 1 (G1), 18%, grade 2 (G2) and 9% grade 3 (G3). Staging investigations were performed in 52% of patients. All serum chromogranin A and 97% of 24-hour urine 5-hydroxyindoleacetic acid tests were normal. The large majority of staging computed tomography (CT) scans were negative (76%) with subgroup analysis showing no G1 patients with CT identified distant disease compared with 38% of G2 and 50% of G3 patients (p < 0.001). G1 patients were more likely to achieve R0/R1 resections compared to G2 (95% vs. 50%, p < 0.001) and G1 patients had significantly better 5-year overall survival (G1: 98%, G2: 67%, G3: 10%, p < 0.001).

CONCLUSION

Tumor grade is important in preoperative workup and surgical decision-making. Biochemical staging may be omitted but staging CT should be considered for patients with grade ≥ 2 lesions. Anatomic resections should be considered for patients with grade 2 disease.

Correlation between clinicopathological characteristics and the clinical prognosis of patients with gastroenteropancreatic neuroendocrine tumors

Gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) are one of the most common types of NETs, accounting for 65-75% of all NETs. However, epidemiological characteristics of patients with GEP-NETs in China are still lacking. The present retrospective study aimed to investigate the local epidemiology of GEP-NETs and assess the prognostic factors in China. The data of 267 patients with GEP-NETs who were admitted to the First Affiliated Hospital of Bengbu Medical College (Bengbu, China) and the Affiliated Hospital of West Anhui Health Vocational College (Lu'an, China) were retrospectively reviewed. The clinical and pathological characteristics of the patients, as well as follow-up information, were collected, and the 5-year survival rate was calculated. Kaplan-Meier curves and log-rank analysis were used to analyze the prognostic factors. The stomach (100/267; 37.5%) was the most common site of GEP-NETs and the liver (25/39; 64.1%) was the most common metastatic site. A total of 166 (62.2%) and 219 (82.0%) patients had positive results for chromogranin A (CgA) and synaptophysin (Syn), respectively. The percentage of patients with tumor grade G1, G2 and G3 was 33.3, 21.0 and 45.7%, respectively. The 5-year overall survival rate was 79.7%, and the age, tumor site, distant metastasis and tumor grading upon diagnosis were all prognostic factors. In conclusion, the present case series investigated the epidemiology and prognostic factors of GEP-NETs in China. CgA and Syn could be used as diagnostic markers for NETs and the stomach was the most common primary tumor site. Lymph node metastasis, tumor site, distant metastasis and tumor grading were important prognostic factors.

Case report: Indocyanine green fluorescence-guided imaging in laparoscope, a more sensitive detection technique of lateral lymph nodes metastases from rectal neuroendocrine tumors

Background

The diagnosis and surgical strategy of lateral lymph node metastases of rectal neuroendocrine tumors are still controversial. At present, the major diagnostic means rely on imaging examinations, but will be affected by the size of lymph nodes leading to false negativity. We provide a new technique to determine lateral lymph node metastases during surgery.

Clinical case

A 68-year-old man developed abdominal pain, bloating and fever for a month. Colonoscopy revealed the mass is 2.4 cm x 2.0 cm in size, with a wide stratum, poor mobility, and a rough but intact surface mucosa. Therefore, rectal neuroendocrine tumors (R-NET) were diagnosed. Multiple imaging methods, such as CT, octreotide imaging and endoscopic ultrasonography, have not found lateral lymph node metastases from rectal neuroendocrine tumors. But indocyanine green (ICG)-enhanced near-infrared fluorescence-guided imaging during surgery found left lateral lymph nodes metastases, which was proved by postoperative pathological examination.

Conclusions

We believe that applying ICG-enhanced near-infrared fluorescence-guided imaging in laparoscope can improve the detection of positive LLNs in those R-NET patients who did not reveal LNM on imaging examinations.

Comparable survival benefit of local excision versus radical resection for 10- to 20-mm rectal neuroendocrine tumors

OBJECTIVE

The optimal surgical management for 10- to 20-mm rectal neuroendocrine tumors (RNET) is still a matter of debate. This study aimed to explore the optimal surgical approach for 10- to 20-mm RNET by comparing the outcomes between local excision and radical resection.

METHOD

We extracted clinicopathological information of 10- to 20-mm RNET from the Surveillance, Epidemiology, and End Results (SEER) database. The 1:2 propensity score matching (PSM) method was used to balance the imbalanced baseline covariates (P < 0.05) between the local excision group and radical resection group. A Cox proportional hazards model was used to identify the risk factors associated with cancer-specific survival (CSS) and overall survival (OS).

RESULT

A total of 531 RNET patients 10-20 mm in size were included. Patients receiving radical resection had larger tumor sizes (P < 0.001), higher T stages (P < 0.001), higher N stages (P < 0.001), higher M stages (P = 0.002) and higher grades (P = 0.041). For 10-20 mm RNET patients, radical resection had no survival benefit compared with local excision (CSS: HR = 2.048, 95% CI 0.553-7.576, P = 0.283; OS: HR = 1.090, 95% CI 0.535-2.219, P = 0.813). After 1:2 PSM, there was no significant difference between local excision and radical resection. Radical resection still had no survival benefit over local excision (CSS: HR = 0.449, 95% CI 0.050-4.022, P = 0.474; OS: HR = 1.408, 95% CI 0.488-4.061, P = 0.527). In a multivariate analysis of CSS, age >60 years old (P = 0.005), tumour size 14-20 mm (P = 0.011) and M1 stage (P < 0.001) were identified as independent prognostic factors for worse CSS. In multivariate analysis of OS, age>60 years (P＜0.001), male sex (P = 0.007), black race (P = 0.016), and T2/T3/T4 stage (P = 0.007) were significantly associated with worse OS. N stage was not an independent predictive factor for CSS and OS.

CONCLUSION

This study revealed that for 10- to 20-mm RNET patients, there was no survival benefit for radical resection compared with local excision, which suggested that local excision may be an adequate treatment for these patients.

Nomogram for individually predicting overall survival in rectal neuroendocrine tumours

BACKGROUND

This study aimed to develop a nomogram that predicts the overall survival (OS) of rectal neuroendocrine tumours (NETs).

METHODS

We retrospectively analysed 310 patients with rectal neuroendocrine tumours in 5 hospitals in southern China. All of the patients were assigned to the training set. A multivariable analysis using Cox proportional hazards regression was performed using the training set, and a nomogram was constructed. It was validated on a dataset obtained from the Surveillance, Epidemiology, and End Result (SEER) database of America (n = 547).

RESULTS

In the training set, the nomogram exhibited improved discrimination power compared with the WHO grade guidelines (Herrell's C-index, 0.872 vs 0.794; p < 0.001) and was also better than the seventh AJCC TNM classification (Herrell's C-index, 0.872 vs 0.817; p < 0.001). In the SEER validation dataset, the discrimination was also excellent (C-index, 0.648 vs 0.583, p < 0.001 and 0.648 vs 0.603, p = 0.016, respectively, compared with G grade and TNM classification). Calibration of the nomogram predicted individual survival corresponding closely with the actual survival.

CONCLUSIONS

We developed a nomogram predicting 1- and 3-year OS of patients with rectal neuroendocrine tumours. Validation revealed excellent discrimination and calibration, suggesting good clinical utility.

The ENETS TNM staging and grading system accurately predict prognosis in patients with rectal NENs

BACKGROUND

Factors associated with rectal NENs prognosis are poorly investigated.

AIM

To evaluate the prognostic role of the ENETs staging and grading systems in rectal NENs.

METHODS

Tertiary referral, multicenter, retrospective study. Factors associated with OS and PFS were investigated by Cox-regression analysis, with best size cut-offs calculated by ROC analysis.

RESULTS

Of 100 patients (mean age 55, 45% male, mean size 16.2 mm) 62, 5, 10 and 23 were TNM stage 1 to 4, and 63, 15 and 22 were G1, G2 and G3. Primary treatment was endoscopic snare resection in 62%, endoscopic mucosal resection/endoscopic submucosal dissection in 10%, surgery in 20% and medical treatment in 8%. The best size cut-offs to predict OS and PFS were 10 and 12 mm. During a mean follow-up of 40.7 months 12% died and 26% progressed. The 5-year OS and PFS were 79.5% and 65.2%. Stage IV and G3 were associated with worse OS (HR 8.16; p = 0.002; HR 15.57; p = 0.0004) and PFS (HR 14.26 p < 0.0001; HR 6.42; p = 0.0007).

CONCLUSION

Both staging and grading accurately predict rectal NENs prognosis. Size alone has limited accuracy as 26% of patients with stage IV and 16% with G3 have a primary tumour≤10 mm.

Endoscopic, transanal, laparoscopic, and transabdominal management of rectal neuroendocrine tumors

Rectal neuroendocrine tumors (RNET) are rare tumors but their prevalence is constantly increasing due to a prolonged survival and rising incidence related to a growing number of colonoscopies and improved knowledge. Their main prognostic determinant is tumor stage. While most RNET are localized, their management should be tailored depending on the presence or absence of the factors predictive of lymph-node metastases including tumor size, endoscopic aspect, T stage, grade and lymphovascular invasion. Endoscopic ultrasonography is the most relevant technique for locoregional assessment. Low-risk RNET can be treated using advanced endoscopic resection techniques or transanal endoscopic microsurgery, in expert centers because they require technicity and experience. Conversely, radical surgery with lymphadenectomy should be proposed in the presence of any pejorative factor. The long-term evolution of RNET remains to be specified, and prospective studies should be conducted in order to determine the relevance of the current management strategies.

Clinical analysis of 547 patients with neuroendocrine tumors in a Chinese population: A single-center study

BACKGROUND

Neuroendocrine tumors (NETs) are rare, which has resulted in a lack of published data on their epidemiology and clinical features. We therefore aimed to investigate the epidemiology, clinical features, treatments, and prognosis of patients with NETs.

METHODS

The clinicopathologic characteristics of 547 patients who were pathologically diagnosed with NETs were retrospectively analyzed, including age, sex, primary and metastatic sites, symptoms, pathology, treatment, and prognosis.

RESULTS

The 547 patients had a wide age range (9-87 years), with a male to female ratio of 1:1.1. The primary tumor sites included 413 in the digestive system, 74 in the lung, 15 in the mediastinum, 8 in unknown sites, and 37 in other sites. Of the 413 patients with digestive system NETs, the pancreas, rectum, and stomach were the most common primary sites. Blood metastases were found in 84 patients at initial diagnosis, and the liver, bone, and lung were the most frequent sites of metastasis. Lymph node metastases were found in 82 patients at initial diagnosis. Surgery and chemotherapy were the most widely applied treatments. Statistical analysis showed that age <50 years, female sex, lower-grade tumor, no distant metastasis, intestinal NET and surgery indicated a favorable prognosis.

CONCLUSIONS

A difference between China and other countries is that small intestinal NETs are quite common in other countries but are rare in China. In China, the most common primary sites are the pancreas, rectum, and stomach. Furthermore, no unified treatments exist, though prognoses could be improved by using methods such as surgery, targeted therapies, and somatostatin analogs.

CLINICAL TRIAL REGISTRATION

This study was not a clinical trial.

Long-term outcomes according to additional treatments after endoscopic resection for rectal small neuroendocrine tumors

The present study aimed to investigate treatment strategies determining additional treatment after endoscopic resection (ER) of rectal neuroendocrine tumor (NET)s and long-term outcomes of endoscopically resected rectal NETs. We analyzed a total of 322 patients medical records of patients who underwent ER for rectal NETs. Rectal NETs initially resected as polyps and treated with conventional endoscopic mucosal resection (EMR) were observed more frequently in the non-curative group (P = 0.041 and P = 0.012, respectively). After ER, only 44 of the 142 patients (31.0%) who did not meet the criteria for curative resection received additional salvage treatment. In multivariate analysis, lesions diagnosed via biopsies (OR, 0.096; P = 0.002) or suspected as NETs initially (OR, 0.04; P = 0.001) were less likely to undergo additional treatment. Positive lymphovascular invasion (OR 61.971; P < 0.001), positive (OR 75.993; P < 0.001), or indeterminate (OR 13.203; P = 0.001) resection margins were more likely to undergo additional treatment. Although lymph node metastasis was found in 6 patients, none experienced local or metastatic tumor recurrence during the median follow-up of 40.49 months. Long-term outcomes after ER for rectal NETs were excellent. The prognosis showed favorable outcomes regardless of whether patients receive additional salvage treatments.

Curative and palliative surgery in patients with neuroendocrine tumors of the gastro-entero-pancreatic (GEP) tract

The incidence of neuroendocrine tumors (NET) increases with age. Lately, the diagnosis of NET was mainly caused by early detection of small NET (<1 cm) in the rectum and stomach, which are depicted by chance during routine and prophylactic endoscopy. Also in patients with large and metastatic pancreatic and intestinal tumors thorough pathologic investigation with use of different immunohistologic markers discovers more neuroendocrine tumors with low differentiation grade (G2-G3) and more neuroendocrine carcinomas (NEC), nowadays, than in former times. While gastric and rectal NET are discovered as small (<1 cm in diameter) and mainly highly differentiated tumors, demonstrating lymph node metastases in less than 10% of the patients, the majority of pancreatic and small bowel NET have already metastasized at the time of diagnosis. This is of clinical importance, since tumor stage and differentiation grade not only influence prognosis but also surgical procedure and may define whether a combination of surgery with systemic biologic therapy, chemotherapy or local cytoreductive procedures may be used. The indication for surgery and the preferred surgical procedure will have to consider personal risk factors of each patient (i.e. general health, additional illnesses, etc.) and tumor specific factors (i.e. tumor stage, grade of differentiation, functional activity, mass and variety of loco regional as well as distant metastases etc.). Together they define, whether radical curative or only palliative surgery can be applied. Altogether surgery is the only cure for locally advanced NET and helps to increase quality of life and overall survival in many patients with metastatic neuroendocrine tumors. The question of cure versus palliative therapy sometimes only can be answered with time, however. Many different aspects and various questions concerning the indication and extent of surgery and the best therapeutic procedure are still unanswered. Therefore, a close multidisciplinary cooperation of colleagues involved in biochemical and localization diagnostics and those active in various treatment areas is warranted to search for the optimal strategy in each individual patient. How far genetic screening impacts survival remains to be seen. Since surgeons do have a central role in the treatment of NET patients, they have to understand the need for integration into such an interdisciplinary team.

Neuroendocrine Gastroenteropancreatic Tumors: Where Are We?

AIMS

Neuroendocrine gastroenteropancreatic tumors are infrequently found neoplasms. Our objective was to analyze the survival rates for all sites that they occur in by studying different variables.

MATERIALS AND METHODS

A retrospective study was carried out using records for a 7-year period from January 1, 2008 to December 31, 2014 on neuroendocrine gastroenteropancreatic tumors patients diagnosed at the Pontevedra-Salnés Hospital Complex. The variables used were as follows: age at diagnosis, tumor size, presence or absence of metastases at diagnosis, cell proliferation index, Ki-67 of each tumor, treatments received, postdiagnosis survival time, existence or not of tumor progression, and time from diagnosis to progression and from diagnosis to mortality. In relation to treatments, the information recorded was whether the treatment was endoscopic, surgical, or pharmacological.

RESULTS

Ninety-three neuroendocrine tumors made up a ratio of 4.42 cases per 100,000 inhabitants per annum. The median patient follow-up time was 44 months. The overall 5-year survival rate for patients who were followed up for a minimum of 60 months (49 patients) was 65.3%. The progression-free survival was 75.6% for 41 patients who were followed up for a minimum of 60 months. The survival rate for patients receiving endoscopic treatment was 100%, as there was no patient mortality recorded for those treated by endoscopic resection during the follow-up period.

CONCLUSION

Pancreatic neuroendocrine tumors may be managed conservatively in elderly patients by either monitoring them with imaging studies or treating them with somatostatin analogs. In the case of digestive tract tumors (stomach, duodenum, and rectum) that meet the criteria for endoscopic resection, this is a reliable and safe technique in the long term.

Elevated E2F7 expression predicts poor prognosis in human patients with gliomas

E2F transcription factors have been studied extensively in a broad range of organisms as major regulators of cell cycle, apoptosis, and differentiation. The E2F family includes the atypical member E2F7, which has been rarely studied in gliomas. The aim of this study is to determine the expression status of E2F7 in gliomas, its relationship to clinicopathological features, and patients' outcome. The mRNA levels of E2F7 in the human brain and different grades of gliomas were analysed using datasets from the publically available Oncomine database. One of the most significant co-expression factors, CDK1, together with E2F7, was further validated by immunohistochemistry in 90 different grades of gliomas. Furthermore, univariate and multivariate analyses were performed to identify prognostic variables relative to patient and tumour characteristics and treatment modalities. E2F7 mRNA expression was found to be elevated in gliomas by Oncomine-database analysis. Immunohistochemistry showed an increase in E2F7 labelling index in high- versus low-grade gliomas (62.1±11.8% vs. 18.9±10.2%, p<0.0001). There was a positive correlation between E2F7 and CDK1 immunoreactivity (Spearman r=0.446, p=0.037). Clinicopathological evaluation suggested that E2F7 expression was associated with tumour grade (p<0.0001) and recurrence (p=0.025). In Cox multivariate analysis, pathological classification and recurrence were independent prognostic factors of gliomas, and E2F7 was significantly related to progression-free survival (p=0.011), but not overall survival (p=0.062). Our findings suggested that E2F7 might act as an independent prognostic factor of gliomas and might constitute a potential therapeutic target for this disease.

Analysis of the factors affecting lymph node metastasis and the prognosis of rectal neuroendocrine tumors

OBJECTIVE

To analyze the factors affecting lymph node metastasis and the prognosis of rectal neuroendocrine tumors after surgical treatment.

METHODS

A retrospective analysis was conducted using the clinical data from 156 cases of rectal neuroendocrine tumors during the period of January 1999 to December 2013. The Kaplan-Meier method was used to calculate the survival time, Cox regression analysis was performed for statistical analysis of clinicopathological factors that may be associated with lymph node metastasis and prognosis, and correlation analysis was carried out using binary logistic regression.

RESULTS

The overall 5-year survival rate of the entire group was 95.7%. Multivariate analysis showed that the depth of invasion was an independent prognostic factor (P < 0.001). The incidence of lymph node metastasis was 7.7% (12/156), and logistic regression analysis showed that lymph node metastasis was related to the depth of invasion (P = 0.003) and tumor diameter (P = 0.006).

CONCLUSION

The surgical approach of rectal neuroendocrine tumors should be selected based on a comprehensive consideration of factors such as tumor size, depth of invasion and lymph node metastasis.

Primary carcinoid tumor of the kidney with estrogen and progesterone receptor expression

Primary carcinoid tumors are uncommon neoplasms in the kidney. The current study presents a case of primary carcinoid tumor of the kidney in a 49-year-old female who suffered from painless gross hematuria for half a month. Left hydronephrosis, a horseshoe kidney and a space-occupying lesion of the left ureter were found by abdominal computed tomography scans and ultrasonic testing. Surgery was performed and an oval tumor was found under the left ureter; the tumor and left kidney were excised completely. The neoplasm was composed of solid nests of cells, trabeculae, adenoid structures and anastomosing cords in a loose and myxoid background. The tumor cells, which were consistent in volume, exhibited centrally oval nuclei with inconspicuous nucleoli, and eosinophilic finely granular cytoplasm. Upon immunohistochemical staining, the neoplastic cells were positive for AE1/AE3, vimentin, synaptophysin, chromogranin A, estrogen receptor and progesterone receptor, while being negative for epithelial membrane antigen, inhibin A, cluster of differentiation (CD)99, S-100 and CD10. Based on the histological characteristics, a diagnosis of primary carcinoid tumor of the left kidney was formed. The patient did not receive further treatment. The total follow-up period was 18 months after the surgery and repeated imaging examinations every 6 months revealed no recurrence.