Primary Renal Carcinoid: Two Rare Cases at a Single Center

Pathogenesis, diagnosis and treatment of primary renal well-differentiated neuroendocrine tumors: a review of the literature

Neuroendocrine tumors (NETs) are a rare type of neoplasm that originate from neuroendocrine cells and peptide neurons. Primary renal well-differentiated NETs are extremely rare, and only a few cases have been reported worldwide. In this study, we present a new case of primary renal well-differentiated NET at our institution, followed by a literature review. A systematic search was conducted using various search terms to identify relevant literature on primary renal well-differentiated NETs from 2021 to present. The study analyzed the clinical features, age, gender, tumor size, location, gross pathology, light microscopy, and immunohistochemical results of 32 cases of primary renal well-differentiated NETs. The findings suggest that these tumors are rare and have nonspecific clinical and imaging features. The diagnosis heavily relies on immunohistochemical analysis. Primary renal well-differentiated NETs are associated with low malignant potential and a favorable prognosis. Surgical resection is the preferred treatment, and long-term follow-up is necessary to monitor the patient's condition.

Primary renal neuroendocrine neoplasms: A systematic literature review, report of four local cases, and original survival analysis of 63 patients from a national registry 2012-2018

Primary renal neuroendocrine neoplasms (NEN) are rare. We aimed to conduct a systematic review, present local cases, and analyse data from the England's National Cancer Registration and Analysis Service (NCRAS) to provide comprehensive evidence on clinical experience, incidence, and survival to better characterize these tumours. First, a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method; second, a synthesis of local cases; and, finally, a retrospective population-based cohort analysis of renal NEN recorded between 2012 and 2018 on NCRAS were performed. Kaplan-Meier estimator was used to calculate overall survival and Cox proportional hazard regression to identify prognostic factors. Systematic review identified 48 articles and the evidence was summarized and presented. We reported data from four local cases presenting with abdominal and back pain but without carcinoid syndrome. In population-based analysis, we identified 63 cases of renal NEN between 2012 and 2018 from the registry. Age-standardized incidence was 0.09-0.32 per million with a median age of 64 years (interquartile range = 48-72 years). Survival was worse in males and those aged 64 years and over. Five-year survival for renal neuroendocrine tumours (NET) was 69.8% (95% confidence interval = 66.6-72.7) and neuroendocrine carcinomas (NEC) was 38.4% (95% confidence interval = 34.6-42.0). No independent predictive factor was identified in the multivariable analyses. We have given a systematic review of evidence, published local experience, and reported incidence and survival of renal NEN in England for the first time. We have provided clinicians with evidence on diagnosis and proposed a treatment algorithm of theses rare tumours. The incidence and median age of presentation in England is similar to other published series. Renal NET has better survival than renal NEC as expected. A uniform classification system would reduce inconsistencies in reporting and standardize treatment decisions for this neoplasia.

Clinical and Pathological Features of Primary Renal Well-Differentiated Neuroendocrine Tumor

Primary carcinoid tumor of the kidney is an extremely rare well-differentiated neuroendocrine tumor, which is generally a low-grade malignant cancer with a good prognosis. Carcinoid tumors are rarely found in the urinary system. Here, we report a 34-year-old woman with primary renal well-differentiated neuroendocrine tumor who underwent nephron sparing surgery and no evidence of recurrence or distant metastasis was found during routine follow-up. We searched the case of renal carcinoid with the search phrase "carcinoid [title] and kidney [title]" and "carcinoid [title] and renal [title]" using the PubMed and restricted the search to articles published in English since 2013. The clinical manifestations, age, sex, tumor size, location, gross pathology, light microscopy and immunohistochemistry were analyzed. A total of 28 cases of renal carcinoid were retrieved from PubMed. Higher proportion of positive labeling of CgA, Syn, NSE and CD56 are most valuable in the diagnosis of primary renal well-differentiated neuroendocrine tumor. At present, radical nephrectomy remains the gold standard in the curative-intent therapy for well-differentiated neuroendocrine carcinoma of kidney, in metastatic renal carcinoid, long-term use of octreotide may be an effective adjuvant therapy.