MEN'S HEALTH MATTERS:Simple renal cysts are very common and the majority do not require any intervention
Q I am a 55-year-old man and had an abdominal ultrasound scan last week because of vague upper abdominal discomfort. My general practitioner has told me that I have a four centimetre cyst in my kidney. He called it a simple cyst and said that there was no need to worry about it. He is arranging further tests for my abdominal discomfort. What is a kidney cyst and should I worry about kidney cancer? Should I have this cyst removed?
AA kidney or renal cyst as it is called is an enclosed sac or pouch that usually contains liquid or semisolid material. These cysts are classified based on the appearance of the fluid-filled lesions and are generally referred to as simple or complex renal cysts. The main concern is the distinction between benign (non-cancerous) and malignant cysts.
The most common type is the “simple renal cyst” which is a small pocket filled with fluid and located within the kidney. The simple cyst is very common and has no risk of becoming a kidney cancer. They can range in size from a few millimetres to many centimetres in diameter, and the wall of the cyst is very thin and has no irregularities in it. Simple cysts are most commonly diagnosed as an incidental finding such as in your case following an abdominal scan performed for some non-associated reason. They vary widely in size and bilateral renal cysts refer to the presence simple cysts in both the kidneys.
Renal cysts are very common and their prevalence increases with age. It is estimated that more than 50 per cent of people over 50 years have them.
Renal cysts can be present at birth (congenital) or acquired later due to a number of underlying diseases and disorders including obstruction in the kidney tubules.
On rare occasions, one can be genetically predisposed to getting kidney cysts. Polycystic kidney disease is an inherited disorder generally associated with multiple simple cysts in both kidneys and can be associated with the presence of liver cysts. This disorder leads to kidney failure in later life.
Renal cysts are more common among people with medullary cystic disease, medullary sponge kidney and chronic renal failure. Those who undergo frequent dialysis, especially haemodialysis, are susceptible to develop renal cysts.
In the majority of people simple renal cysts cause no symptoms. In fact, many people with renal cysts are not aware that they have them and no intervention is necessary for these small and benign renal cysts. If sufficiently large, they can cause backaches and a dragging sensation in the loin area. Sudden onset severe flank pain may follow bleeding into the cyst.
Rarely, a simple renal cyst will require intervention to relieve pain. Options include aspiration (sucking the fluid out of the cyst) and injection of a sclerosing agent such as sterile alcohol (particularly ethanol) which will cause scarring and help prevent further reaccumulation of the fluid.
Unfortunately, the majority of cysts recur after this treatment and keyhole surgery may be necessary whereby the wall of the cyst is cut out to prevent it from re-forming. If there is any suspicion that a cyst is cancerous, then surgical removal generally with keyhole surgery is indicated.
Renal cysts may be imaged using ultrasound, CT (computed tomography) and magnetic resonance imaging (MRI) scan. Your doctor will advise you on the most appropriate imaging modality.
The other type of cyst is called a “complex cyst”. This term refers to a spectrum of cysts that have characteristics that differentiates them from simple cysts and increases the risk of kidney cancer. A complex cyst is different from a simple kidney cyst in that it contains irregularities such as an irregular outer shape or it may contain irregularities within.
Complex renal cysts may have septations (walls within the same cyst), calcifications (deposition of calcium) and enhancements (a part of the cysts receives blood supply).
Some symptoms that may develop due to complicated renal cysts are kidney pain, difficulty in urination, frequent urination, presence of blood in urine, hypertension (blood pressure) or abdominal and loin discomfort.
Many complex renal cysts have a low risk for being or becoming a kidney cancer. However, solid enhancing material inside of a complex kidney cyst requires further evaluation by a urologist as it is suspicious for kidney cancer until proven otherwise and may require treatment. Often, complex renal cysts may be treated with surveillance to see if the cyst changes in any way over time.
In summary, simple renal cysts are very common and in general do not cause any symptoms and the majority do not require any intervention.
This weekly column is edited by Thomas Lynch, consultant urological surgeon, St James’s Hospital, Dublin, with a contribution from Mr Kevin OConnor, urology specialist registrar, St James’s Hospital, Dublin.
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