What is the management for a 0.7 cm renal cyst?

Management of a 0.7 cm Renal Cyst

A 0.7 cm renal cyst requires no intervention and no routine follow-up imaging, as this represents a simple renal cyst that is benign and asymptomatic. 1, 2

Initial Characterization

The first step is to confirm this is a simple cyst using appropriate imaging:

• Ultrasound is the preferred initial imaging modality for detecting and characterizing simple renal cysts due to its non-invasive nature, lack of radiation exposure, and cost-effectiveness 2
• Simple renal cysts are characterized by well-defined margins, absence of internal echoes on ultrasound, and no contrast enhancement on CT or MRI 1, 2
• If the cyst meets these criteria for a simple cyst (Bosniak I or II), it has approximately 0% malignancy risk 3, 1, 2

Management Algorithm

For a confirmed simple renal cyst of 0.7 cm:

• No intervention is required for asymptomatic simple renal cysts regardless of size 1, 2
• No routine follow-up imaging is necessary for confirmed Bosniak I and II cysts 1, 2
• The natural history of simple cysts shows that 86% increase in size over time, but this growth is not associated with development of complex features or malignancy 4

When to Reconsider

You should only pursue further evaluation or intervention if:

• The cyst develops new characteristics such as septations, wall thickening, or solid components on any future imaging obtained for other reasons—these changes warrant investigation due to increased malignancy risk 1
• The patient develops symptoms attributable to the cyst (pain, hematuria, hypertension), though this is extremely unlikely with a 0.7 cm cyst 5, 6
• The imaging characteristics are not consistent with a simple cyst, requiring classification using the Bosniak system with multiphase CT or MRI 3, 2

Important Caveats

• A solitary cyst in a child requires follow-up imaging as it may indicate autosomal dominant polycystic kidney disease (ADPKD) if there is a positive family history 2
• For adults, simple cysts are extremely common (prevalence approximately 5%) and increase with age 5
• If this cyst were discovered incidentally and you're uncertain about its characteristics, obtain high-quality cross-sectional imaging (CT or MRI with and without contrast) to properly classify it using the Bosniak system before dismissing it 3, 2