Simple and complex renal cysts in adults
- William M Bennett, MD
William M Bennett, MD
- Medical Director
- Legacy Good Samaritan Transplant Services
- Jonathan B Kruskal, MD, PhD
Jonathan B Kruskal, MD, PhD
- Section Editor — Kidney Disease
- Professor of Radiology
- Harvard Medical School
- Jerome P Richie, MD, FACS
Jerome P Richie, MD, FACS
- Section Editor — Cancer of the Urethra, Penis, and Ureter
- Section Editor — Urologic Surgery
- Section Editor — Prostate Cancer
- Elliott Carr Cutler Professor of Surgery
- Harvard Medical School
Renal cysts result from genetic or nongenetic processes and occur in a variety of diseases in adults and children. The most common causes of radiologically evident renal cysts in adults are simple renal cysts, which will be discussed here; autosomal dominant polycystic kidney disease (PKD); and acquired cystic disease in patients with end-stage renal disease (ESRD) after several years of dialysis, particularly hemodialysis. (See "Renal manifestations of autosomal dominant polycystic kidney disease" and "Course and treatment of autosomal dominant polycystic kidney disease" and "Acquired cystic disease of the kidney in adults".)
Smaller cysts, usually <1 cm in diameter, also occur in medullary sponge kidney, autosomal recessive PKD, and autosomal dominant interstitial kidney disease (previously called medullary cystic kidney disease). (See "Medullary sponge kidney" and "Autosomal recessive polycystic kidney disease in children" and "Autosomal dominant interstitial kidney disease (medullary cystic kidney disease)".)
Other unusual causes of renal cysts in adults are von Hippel-Lindau disease, tuberous sclerosis complex, and nephronophthisis. (See "Clinical features, diagnosis, and management of von Hippel-Lindau disease" and "Renal manifestations of tuberous sclerosis complex", section on 'Renal cysts' and "Genetics and pathogenesis of nephronophthisis", section on 'Pathogenesis'.)
An overview of the renal cyst classification system, our recommended approach to complex renal cysts in adults, and a discussion of simple renal cysts are presented in this topic review. The evaluation of a solid renal mass is discussed separately. (See "Diagnostic approach, differential diagnosis, and treatment of a small renal mass".)
CHARACTERISTICS OF SIMPLE AND COMPLEX RENAL CYSTS
Renal cysts are categorized as simple or complex. Simple renal cysts are commonly observed in normal kidneys, with an increasing incidence as individuals age . They are benign, asymptomatic lesions that rarely require treatment. (See 'Simple renal cysts' below.)
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- CHARACTERISTICS OF SIMPLE AND COMPLEX RENAL CYSTS
- BOSNIAK CLASSIFICATION OF RENAL CYSTS
- MANAGEMENT BY BOSNIAK CATEGORY
- Category I and II
- Category IIF
- Category III
- - Magnetic resonance imaging
- - Percutaneous needle biopsy
- Category IV
- SIMPLE RENAL CYSTS
- Clinical features
- - Ultrasonography
- - Computed tomography scan
- Diagnosis of complications
- Differential diagnosis
- SUMMARY AND RECOMMENDATIONS