title: Cystic renal cell carcinomas: do they grow, metastasize, or recur?
abstract: OBJECTIVE
  The purpose of this study is to evaluate the interval growth, tumor recurrence, and metastatic disease occurrence of cystic renal cell carcinoma (RCC).
  
  
  METHODS
  Pre-and posttreatment imaging of 47 histologically proven cystic RCCs, with at least 6 months of pretreatment imaging monitoring or at least 2 years of posttreatment imaging follow-up, or both, was retrospectively reviewed. Tumor morphologic features, preoperative growth, histologic typing and grading, and the incidence of tumor recurrence or metastasis were evaluated. Growth rate of tumors were compared among various histologic subtypes and Fuhrman grades.
  
  
  RESULTS
  Of 47 tumors, 27 (57.5%) were clear cell RCCs, 12 (25.5%) were multilocular RCCs, and eight (17%) were papillary cystic RCCs. Overall, 26 (55.3%) tumors were graded as Fuhrman grade 2, 17 (36.1%) were Fuhrman grade 1, and one tumor was Fuhrman grade 3. Of the 26 tumors with a minimum of 6 months of pretreatment imaging monitoring, 19 (73%) did not show a significant increase in tumor size. The differences in mean growth among the Fuhrman grades and different subtypes were not statistically significant. The average duration of posttreatment follow-up was 51 months. There were no local recurrences among the 43 patients who underwent posttreatment imaging, except for one patient who had metastasis at preoperative clinical presentation.
  
  
  CONCLUSIONS
  Cystic RCCs exhibit slow indolent growth, if any, and show no significant metastatic or recurrence potential, with excellent clinical outcomes. We raise the need for revisiting current imaging protocols that may involve frequent pre-and posttreatment imaging in cystic RCCs.
authors.affiliation: Joint Department of Medical Imaging, University Health Network-Mount Sinai Hospital and Women's College Hospital, University of Toronto, 3-957, 610 University Ave, Toronto, ON M5G 2M9, Canada.
authors.forename: Kartik
authors.initials: K
authors.lastname: Jhaveri
authors.forename: Priya
authors.initials: P
authors.lastname: Gupta
authors.forename: Azadeh
authors.initials: A
authors.lastname: Elmi
authors.forename: Lior
authors.initials: L
authors.lastname: Flor
authors.forename: Hadas
authors.initials: H
authors.lastname: Moshonov
authors.forename: Andrew
authors.initials: A
authors.lastname: Evans
authors.forename: Michael
authors.initials: M
authors.lastname: Jewett
mesh_terms: D002292:Carcinoma, Renal Cell / Q000473:pathology* / Q000601:surgery; D017115:Catheter Ablation; D003287:Contrast Media; D003952:Diagnostic Imaging; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology* / Q000601:surgery; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009392:Nephrectomy; D011379:Prognosis; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D015996:Survival Rate; D014283:Triiodobenzoic Acids
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; C064925:gadodiamide; C044834:iodixanol; D019786:Gadolinium DTPA