title: Renal neuroendocrine tumours: a clinicopathological study.
abstract: OBJECTIVE
  To report cases of primary neuroendocrine tumours (NETs) of the kidney, including carcinoid tumour, large cell neuroendocrine carcinoma (LCNEC) and small cell carcinoma (SCC), which show a wide range of NE differentiation and biological behaviour, and are exceedingly rare.
  
  
  METHODS
  The clinicopathological features of all nine renal NETs diagnosed during a 7-year period were reviewed.
  
  
  RESULTS
  Six carcinoids, two SCC and one LCNEC were identified from 2780 kidney tumours. No patient had carcinoid syndrome or other NE symptoms. Three of six carcinoids and no SCC/LCNEC arose in horseshoe kidneys. The mean size of the six carcinoids and three SCC/LCNEC was 4.8 cm and 12.2 cm, respectively. No carcinoid had tumour necrosis or mitosis. By contrast, three SCC/LCNEC had extensive tumour necrosis and brisk mitosis. All renal NETs were positive for synaptophysin but were variably positive for chromogranin and CD56. Three of six carcinoid tumours were confined to the kidney, and four of five patients were disease-free at a mean (range) of 26 (6-74) months. One patient with nodal metastases has had no recurrence and another died with liver metastases. Three patients with SCC/LCNEC each presented with locally advanced disease and extensive lymphadenopathy; two of them died from distant metastasis or local tumour progression, and the third is currently alive with disease.
  
  
  CONCLUSIONS
  Various NETs can occur in the kidney, but rarely. Renal carcinoids have a variable clinical course; SCC and LCNEC are associated with poor clinical outcomes. The diagnosis of NETs, especially LCNEC, requires awareness of their rare occurrence and prudent use of immunohistochemical NE markers.
authors.affiliation: Glickman Urological Institute, Cleveland Clinic, Cleveland, Ohio, USA. laneb@ccf.org
authors.forename: Brian R
authors.initials: BR
authors.lastname: Lane
authors.forename: Farah
authors.initials: F
authors.lastname: Chery
authors.forename: George
authors.initials: G
authors.lastname: Jour
authors.forename: Linda
authors.initials: L
authors.lastname: Sercia
authors.forename: Cristina
authors.initials: C
authors.lastname: Magi-Galluzzi
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Novick
authors.forename: Ming
authors.initials: M
authors.lastname: Zhou
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D018358:Neuroendocrine Tumors / Q000473:pathology*; D011379:Prognosis