title: Cystic partially regressed clear cell renal cell carcinoma: a potential mimic of multilocular cystic renal cell carcinoma.
abstract: OBJECTIVE
  To study clear cell renal cell carcinomas with predominant cystic and sclerotic components, in which a solid epithelial component precluded a diagnosis of multilocular cystic renal cell carcinoma. We designated these tumours 'cystic partially regressed clear cell renal cell carcinoma.'
  
  
  RESULTS
  Twenty-seven tumours were studied, from patients with a median age of 58 years; the stage was most often pT1 (89%). The Fuhrman grade was 2 (48%), 1 (33%), or 3 (19%). The solid epithelial component constituted up to 30% of the tumour volume (median, 10%), whereas the cystic component constituted 15-80% (median, 65%), and the sclerotic component 10-70% (median, 20%). Thin fibrovascular septa lined by cells with clear cytoplasm were almost always present, resembling multilocular cystic renal cell carcinoma. Both zones of sclerosis and fibrovascular septa often contained inconspicuous epithelial cells. Sclerotic areas ranged in appearance from a cellular fibroblastic reaction to scar-like with a residual network of capillaries resembling haemangioma. No patient developed recurrence or metastasis.
  
  
  CONCLUSIONS
  Cystic partially regressed clear cell renal cell carcinoma is an uncommon pattern of clear cell renal cell carcinoma, being composed of cysts with solid epithelial and sclerotic components that differentiate it from multilocular cystic renal cell carcinoma.
authors.affiliation: Department of Pathology and Laboratory Medicine, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Sean R
authors.initials: SR
authors.lastname: Williamson
authors.forename: Gregory T
authors.initials: GT
authors.lastname: MacLennan
authors.forename: Antonio
authors.initials: A
authors.lastname: Lopez-Beltran
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Montironi
authors.forename: Puay Hoon
authors.initials: PH
authors.lastname: Tan
authors.forename: Guido
authors.initials: G
authors.lastname: Martignoni
authors.forename: David J
authors.initials: DJ
authors.lastname: Grignon
authors.forename: John N
authors.initials: JN
authors.lastname: Eble
authors.forename: Muhammad T
authors.initials: MT
authors.lastname: Idrees
authors.forename: Marina
authors.initials: M
authors.lastname: Scarpelli
authors.forename: Liang
authors.initials: L
authors.lastname: Cheng
mesh_terms: D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000175:diagnosis / Q000473:pathology*; D003560:Cysts / Q000473:pathology; D003937:Diagnosis, Differential; D004848:Epithelium / Q000473:pathology; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D009626:Terminology as Topic
keywords: classification; cystic partially regressed clear cell renal cell carcinoma; differential diagnosis; immunohistochemistry; kidney; multilocular cystic renal cell carcinoma; neoplasia