Bladder, ureter & renal pelvis

Neuroendocrine neoplasms

Well differentiated neuroendocrine tumor

Topic Completed: 1 December 2014

Minor changes: 18 May 2021

Copyright: 2003-2021,, Inc.

PubMed Search: Bladder carcinoid tumor

Turki Al-Hussain, M.D.
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Cite this page: Al-Hussain T. Well differentiated neuroendocrine tumor. website. Accessed November 27th, 2021.
Definition / general
  • Rare low grade neuroendocrine carcinoma, similar to counterparts at other sites
  • Formerly called carcinoid tumor
  • Usually ages 47-69 years
  • Bladder neck and trigone
Clinical features
  • Rare, < 50 cases described
  • Patients present with hematuria
  • No carcinoid syndrome
  • Behavior is difficult to predict (Arch Pathol Lab Med 2006;130:1693); occasionally produces metastases and death
Case reports
  • Excision is usually curative, but behavior may not be predictable
Gross description
  • Usually 1-2 cm
  • Smooth-surfaced sessile polypoid nodules covered by urothelium
Microscopic (histologic) description
Positive stains
Electron microscopy description
  • Neuroendocrine differentiation
Differential diagnosis
  • Inverted papilloma: lacks salt and pepper chromatin of carcinoid tumors; not invasive
  • Metastasis: clinical history
  • Nested variant of urothelial carcinoma: classic urothelial carcinoma usually present elsewhere; usually no well defined neuroendocrine features
  • Paraganglioma: nests of tumor cells surrounded by S100+ sustentacular cells
  • Direct invasion of carcinoid tumor from appendix: clinical history
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