Simple renal cysts - Renal cystic disease

Simple renal cysts

Definition

These are common, usually asymptomatic benign cysts of the kidney of unknown cause.

Incidence/prevalence

Related to age and sex, with about 1–2% of 30–50 year olds, but as many as 15–30% in over 70 years, having one or more cysts.

Age

Rare under the age of 30.

Sex

M > F (2:1)

Clinical features

Almost always asymptomatic and so tend to be found incidentally on ultrasound, IVU or CT. They have no effect on renal function, except rarely when they may induce hypertension. Occasionally they may become infected or develop haemorrhage and rarely may become malignant.

Macroscopy

There are single or multiple cysts up to 5–6 cm in diameter filled with clear watery fluid, which have a smooth lining.

Investigations

If there are multiple cysts, a diagnosis of adult polycystic kidney disease should be considered. If the cyst looks as if it may have any solid or mixed echogenicity components, a thickened wall, or appears loculated on ultrasound, then further investigation by CT may be indicated, to differentiate a cyst from a possible malignancy. Cyst aspiration/drainage is indicated for infected cysts as diagnosis and treatment.

Management

No specific treatment required, except for complications.