Prevalence of Renal Cysts in Adults

Simple renal cysts are common in adults, with an estimated prevalence of over 30% in individuals over 50 years of age. 1

Epidemiology and Age Distribution

The prevalence of simple renal cysts increases significantly with age, making them one of the most common incidental findings on abdominal imaging 1, 2
In a comprehensive study of healthy Korean adults, the overall prevalence of simple renal cysts was found to be 5.43% across all age groups 2
Renal cysts are occasionally found even in adults under 40 years of age, with a prevalence of approximately 4.7% in this younger population 3
The prevalence increases dramatically with advancing age, with the highest rates seen in individuals over 50 years 1, 2

Age is the strongest independent risk factor for the development of simple renal cysts 2
Other significant risk factors include:
- Higher BMI 2
- Presence of proteinuria 2
- Microscopic hematuria 2
- Reduced estimated glomerular filtration rate 2
- Hypertension 2

Approximately 86% of simple renal cysts increase in size over time 4
The average growth rate of simple renal cysts is approximately 1.43 mm (6.5%) per year 2
Younger patients (under 50 years) tend to have more rapid cyst growth rates compared to older individuals 2
Despite growth over time, simple cysts typically do not develop complex features or malignant transformation 4

Most simple renal cysts remain asymptomatic and do not require intervention 5
In young adults, the presence of simple renal cysts has been associated with a 2.3-fold increased prevalence of albuminuria, independent of other risk factors 3
Simple cysts should be distinguished from more concerning entities such as:
- Autosomal dominant polycystic kidney disease (ADPKD), which has a prevalence of approximately 1 per 1000 in the general population 6
- Bosniak category III and IV cysts, which have significant malignancy risk 7

Ultrasonography is the preferred initial imaging modality for detecting and characterizing renal cysts due to its non-invasive nature and cost-effectiveness 7
Simple renal cysts are characterized by well-defined margins, absence of internal echoes on ultrasound, and no contrast enhancement on CT or MRI 7
MRI is more sensitive than ultrasonography for detecting kidney cysts but is not typically used as first-line due to cost considerations 7
For adults with a positive family history of ADPKD, specific diagnostic criteria exist:
- ≥3 total cysts for ages 15-39 years
- ≥2 cysts in each kidney for ages 40-59 years
- ≥4 cysts in each kidney for age ≥60 years 6

Asymptomatic simple renal cysts generally require no intervention or specific follow-up 7, 5
Cysts with irregular features warrant follow-up to exclude malignant progression 5
Symptomatic cysts may require intervention, with aspiration plus sclerotherapy being more effective than simple aspiration alone 5
A solitary cyst in childhood requires follow-up imaging, particularly in those with a family history of ADPKD 7