Renal Cysts Flashcards
What are renal cysts?
Renal cysts are fluid-filled sacs found in the kidney.
What are the 2 different types of renal cysts?
They can be classified as either simple or complex.
What are simple cysts?
Simple cysts have a well-defined outline and homogeneous features. They are very common in older patients, with prevalence of up to 50% in those over 50yrs.
Simple cysts are thought to develop from the renal tubule epithelium in response to previous ischaemia, however their exact pathophysiology is still not fully understood.
What are complex cysts?
Complex cysts have more complicated structures, including thick walls, septations, calcification, or heterogeneous enhancement on imaging.
They can be classified using the Bosniak classification. All complex cysts have a risk of malignancy and this risk increases with its increasing complexity.
What are the risk factors for renal cysts?
Risk factors for the development of renal cysts include increasing age, smoking, hypertension, and male gender.
Genetic conditions that can cause renal cysts include polycystic kidney disease, tuberous sclerosis, and Von Hippel-Lindau disease.
What is polycystic kidney disease (PKD)?
Autosomal dominant polycystic kidney disease (ADPKD) is an inherited condition caused by mutations in the PKD1 or PKD2 genes, resulting in multiple renal cysts forming in affected individuals.
The condition is also associated with Berry aneurysm formation (leading to subarachnoid haemorrhage), mitral valve disease and liver cysts. Patients will eventually develop end-stage renal failure and may require either dialysis or a renal transplant.
What are the clinical features of renal cysts?
Renal cysts are most likely to be found incidentally on abdominal imaging, as they are usually asymptomatic, especially if simple.
Clinical features however can include flank pain (if a cyst ruptures or becomes infected) or haematuria. Patients with polycystic kidney disease can present with uncontrolled hypertension or even with a flank mass.
What investigations should be ordered for renal cysts?
The definitive diagnosis for a renal cyst is through CT or MRI imaging, with pre- and post-enhancement scans with IV contrast.
Ultrasound often picks up incidental findings of renal cysts, however in such cases, will require further imaging with CT or MRI.
A patient’s serum U&Es should also be checked in known cases, ensuring there is not impact to the patient’s renal function. This should be monitored regularly in patients who have a known genetic risk for renal cyst formation as well.
What scoring system is used to assess renal cysts?
The Bosniak scoring system is the currently accepted method for classifying renal cysts.
Briefly describe Bosniak scoring system
Briefly describe the management of renal cysts
Asymptomatic simple cysts do not normally need any further follow-up or treatment.
Symptomatic simple renal cysts can be managed initially with simple analgesia, however needle aspiration or cyst deroofing may be warranted if significantly impacting the patient.
Complex cysts are managed depending on their Bosniak Stage and this may involve continued surveillance or surgical intervention, including consideration for nephrectomy.
What is the prognosis of renal cysts?
Complications are rare, however can include infection, haemorrhage, and rupture. Complications in simple cysts can make them very hard to differentiate from complex cysts on subsequent imaging.
Prognosis depends on the complexity of the renal cysts and their risk of malignancy.
What differentials should be considered in renal cysts?
The main differential for any renal cyst is cystic renal cell carcinoma and hence should be evaluated accordingly with imaging as required.
