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renal cyst

Epidemiology: 1) overall prevalence 12%; 15% men vs 8% women 2) prevalence increases with age a) 5% of patients 30-40 years b) 25-30% of patients > 50 years c) 35% of patients > 70 years Pathology: 1) average yearly increase in cyst size = 2.8 mm [2] 2) mean # of cysts/kidney increased from 0.8-1.3 over 5 years 3) only predictor of rapid growth is multilocular shape [2] 4) simple cyst: [3] a) non-enhancing b) hairline, thin walls c) no septae or few hairline thin septae 5) complex cyst: [3] a) many thin septae b) thickening of a septum or wall c) nodular calcification Clinical manifestations: - most cysts are asymptomatic Radiology: 1) renal ultrasound 2) computed tomography - evaluate renal function before use of contrast - Bosniak grading system used to characterize renal cysts [4] - renal CT includes a noncontrast phase; a contrast-enhanced, nephrographic phase; & a delayed phase 3) magnetic resonance imaging (MRI) Management: 1) simple cysts: a) no malignant transformation [2,3] b) no further imaging studies or intervention needed [1] 2) complex renal cysts or mass lesions > 4 cm a) simple cysts > 4 cm do not need further evaluation [8] b) ~5% of complex renal cysts eventually found to be malignant [3] c) further evaluation with CT or MRI indicated [1] d) active surveillance may be an acceptable alternative to immediate surgical intervention [5]

Related

polycystic kidney disease

General

cyst kidney disease; renal disease

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, 15, American College of Physicians, Philadelphia 1998, 2009
  2. Journal Watch 22(4):28, 2002 Terada N, Ichioka K, Matsuta Y, Okubo K, Yoshimura K, Arai Y. The natural history of simple renal cysts. J Urol 167:21, 2002 PMID: 11743266 - Terada N, Arai Y, Kinukawa N, Terai A. The 10-year natural history of simple renal cysts. Urology. 2008 Jan;71(1):7-11; discussion 11-2. PMID: 18242354
  3. Journal Watch 23(21):166-67, 2003 Israel GM & Bosniak MA Follow-up CT of moderately complex cystic lesions of the kidney (Bosniak category IIF). AJR AM J Roentgenol 181:627, 2003 PMID: 12933451
  4. Thomas S, Grimm L, Brady MP Renal Cell Carcinoma: Recognition and Follow-up. Medscape. April 18, 2016 http://reference.medscape.com/features/slideshow/renal-cell-carcinoma
  5. Chandrasekar T, Ahmad AE, Fadaak K et al. Natural history of complex renal cysts: Clinical evidence supporting active surveillance. J Urol 2018 Mar; 199:633 PMID: 28941915 http://www.jurology.com/article/S0022-5347(17)77564-7/fulltext
  6. Smith AD, Allen BC, Sanyal R et al. Outcomes and complications related to the management of Bosniak cystic renal lesions. AJR Am J Roentgenol 2015 May; 204:W550 PMID: 25905961
  7. Richard PO, Violette PD, Jewett MA et al. CUA guideline on the management of cystic renal lesions. Can Urol Assoc J 2017 Mar-Apr; 11:E66 PMID: 28360949 Free PMC Article
  8. NEJM Knowledge+ Complex Medical Care
  9. Simple Kidney Cysts http://kidney.niddk.nih.gov/kudiseases/pubs/cysts/index.htm