The Clinical and Uropathological Aspects of Neuroendocrine Tumours of the Bladder: A Review

Özet

Neuroendocrine tumours of the bladder are less common than other histologic types (e.g., urothelial carcinoma, squamous cell carcinoma,adenocarcinoma), constituting 1% of malignant bladder cancers. Based on the “2016 World Health Organization Classification of Tumours of theUrinary System and Male Genital Organs”, neuroendocrine tumours are classified into four subtypes: small cell neuroendocrine carcinoma (SCNC),large cell neuroendocrine carcinoma (LCNC), well-differentiated neuroendocrine tumour (carcinoid tumour) and paraganglioma. SCNC is morecommon than other subtypes, and LCNC is exceedingly rare in the bladder. Although neuroendocrine tumours are not as common as neuroendocrineneoplasms of the lungs, the differential diagnosis of these tumours remains crucial and should be considered in uropathology. Neuroendocrinetumours of the bladder can present with distinctive morphology and grades, similar to their pulmonary counterparts. The knowledge of thisdiagnosis is critical to advance the uropathological field and accelerate drug development with inclusion, rather than exclusion, of patients withSCNC and other variants of neuroendocrine tumours of the bladder. Therefore, in this review, the bladder’s clinical and uropathological aspects ofneuroendocrine tumours are reviewed. This classification provides a useful platform to discuss the aetiology, pathogenesis, clinical and pathologicalcharacteristics and treatment of the neuroendocrine tumours of the urinary bladder. The overall prognosis of urinary bladder neuroendocrinetumours is worse than urothelial carcinoma. Various advances are expected in the clinical characterisation, prognostication and treatment ofneuroendocrine tumours of the bladder with the technologies developed in genetic and cellular investigations.