Primary Renal Well-Differentiated Neuroendocrine Tumors: Analyis of Six Cases from a Tertiary Care Center in North India with Review of Literature

Abstract

Well-differentiated renal neuroendocrine tumors are rare tumors. As their biologic behavior is not fully known, there is a need to know more about these cases. We performed a retrospective chart review of all the cases diagnosed with renal neuroendocrine tumors from January 2016 to December 2020 (five years) in order to understand their clinical features, morphological characteristics and outcome. We included six cases with mean age of 46.2 years (4 males) in our study. All patients underwent radical nephrectomy. Histologically all showed tumor disposed in nests and trabeculae and majority of the tumors belonged to well-differentiated neuroendocrine tumor Grade 1 (WHO criteria of gastoroenteropancreatic neuroendocrine neoplasms). Lymph node metastasis was seen in two cases at the time of clinical presentation. All the tumors were diffusely positive for neuroendocrine tumor markers (synaptophysin, chromogranin, NSE, CD56). Follow-up data was available in all cases with an average follow-up of two years and neither has shown evidence of metastasis or relapse till last follow-up. Role of morphological patterns and immunohistochemical markers is highlighted with the importance of including Ki-67 index in grading them to better understand their outcome.

Prognostic factors and treatment impact on overall survival in patients with renal neuroendocrine tumour

“…Studies suggest that R‐NEN precursor cells arise from renal stem cells that develop towards neuroendocrine differentiation 12 . Previous studies suggest that metastasis is common at the time of diagnosis, typically to the liver or regional lymph nodes, even in patients with well‐differentiated tumours 4,8 . There are a few associated conditions with R‐NEN, specifically horseshoe kidney and renal teratomas 13–15 .…”

“… 12 Previous studies suggest that metastasis is common at the time of diagnosis, typically to the liver or regional lymph nodes, even in patients with well‐differentiated tumours. 4 , 8 There are a few associated conditions with R‐NEN, specifically horseshoe kidney and renal teratomas. 13 , 14 , 15 R‐NENs often share features found in others NENs including immunohistochemical expression of chromogranin A and synaptophysin.…”

“…NENs are composed of tumours linked by histological markers that can arise in any organ, including those that do not harbour neuroendocrine cells 3 . The most common primary sites for NENs are the gastrointestinal tract, lungs and the pancreas 4,5 . These tumours have been difficult to characterize due to their varying biologic behaviour, histology and treatment response 3,6 …”

“… 3 The most common primary sites for NENs are the gastrointestinal tract, lungs and the pancreas. 4 , 5 These tumours have been difficult to characterize due to their varying biologic behaviour, histology and treatment response. 3 , 6 …”