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AnneLumiaho

Renal Cysts

Essentials

  • A solitary cyst is usually a clinically insignificant incidental finding at ultrasonography and does not require further follow-up.
  • In autosomal dominant polycystic kidney disease (ADPKD), cysts increase and the size of kidneys increases with age. Patients with ADPKD may also have cerebrovascular aneurysms, liver cysts, valvular heart disease and hypertension. Family history is important and ultrasonography is diagnostic.

Solitary cysts

  • Solitary renal cysts are associated with ageing and do not usually have clinical significance when detected as incidental findings on ultrasonography (in as many as 50% of patients above 50 years of age). The cysts may be solitary, multiple and bilateral.
  • Acquired cysts are associated with chronic renal failure, in which case the kidneys are small or normal in size and the cysts are small.
  • The sonographic criteria of a benign cyst (picture 1) are:
    • no internal echoes
    • acoustic enhancement behind the cyst
    • sharply defined, imperceptible wall
    • round or oval shape.
  • If all these criteria are met, further evaluation or follow-up is not required http://www.dynamed.com/approach-to/incidental-renal-mass-or-cyst-approach-to-the-patient-22#GUID-7966306D-40B6-4888-99B5-38F291B25C5B.
  • A solitary cyst may also be malignant. Malignant cysts can usually be differentiated from benign cysts by ultrasonography (see above). Additional investigations include computed tomography or needle biopsy performed by a radiologist.

Polycystic kidney disease

Autosomal dominant polycystic kidney disease

  • Inherited as an autosomal dominant trait, meaning that the children of a patient have a 50% risk of inheriting the disease.
  • Its prevalence is 1:400-1:1 000. Its incidence in Finland is 7-8/1 000 000.
  • Cysts develop in both kidneys, increasing and growing with age. The kidneys grow (may weigh up to several kilogrammes), and renal failure develops.
  • About 70% of patients require renal dialysis by the age of 40 to 70 years.
  • The disease is caused by a mutation in either the PKD1 or the PKD2 gene.
    • A mutation in the PKD2 gene causes a clearly milder disease with dialysis required at an average age of 69 years, whereas those with PKD1 disease need dialysis at an average age of 53 years, already.
    • 85% of patients with polycystic disease have PKD1 disease.
  • Most common initial symptoms
    • Abdominal pain
    • Haematuria
    • Hypertension
  • Diagnosis by abdominal ultrasonography
  • Liver cysts are common in these patients but they have no effect on liver function. Cysts may also occur in the pancreas.
  • The risk of cerebrovascular aneurysms is increased in patients with a family history of stroke or aneurysm.
    • These patients should undergo cerebrovascular MRI and if the findings are normal, the examination should be repeated every 5 to 10 years depending on other risk factors.
  • The patients also have an increased risk of valvular heart disease, particularly mitral regurgitation or prolapse or aortic valve regurgitation.
  • Colonic diverticula and hernias are also common.
  • Cysts may be associated with pain from the fibrous capsule of the kidney being stretched. A cyst may rupture causing acute pain and haematuria. A cyst may also become infected.
  • Hypertension is found in as many as 35% of children with the disease.
  • Factors worsening the prognosis of kidney disease include
    • hypertension before the age of 35 years
    • cyst ruptures/haematuria before the age of 35 years
    • male sex
    • mutation in the PKD1 gene
    • GFR decreased at an early stage
    • large size of kidneys.
  • The size of the kidneys can best be measured by MRI. The size can be used to assess the prognosis of the disease.
  • Treatment
  • If parents want it, also children can be investigated by ultrasonography. Gene testing is also possible. If parents do not want diagnostic examinations, at least children's blood pressure should be monitored every 3 years from the age of 5 years on and their urine should be monitored for the possible development of proteinuria.

Recessive polycystic kidney disease (infantile form)

  • Prevalence 1:10 000-1:40 000
  • Typically discovered at birth; the most severe cases can be discovered after the 24th gestational week, already.
    • Milder forms are detected only in childhood or youth.
  • A disease of the liver and the kidneys
    • Liver disease may dominate the clinical picture.
      • Hepatic fibrosis leads to portal hypertension, splenomegaly and oesophageal varices
      • Liver cysts
      • Enlarged liver and bile ducts
  • In 50% of patients, renal failure requiring dialysis develops within the first year of life.
    • Only a few patients cope without dialysis until the age of 40 to 50 years.
  • 75% of patients have hypertension
  • There is no specific treatment available.
  • See further information in Orphanet http://www.orpha.net/consor/cgi-bin/Disease_Search.php?lng=EN&data_id=97&Disease_Disease_Search_diseaseGroup=Polycystic-kidney-disease--autosomal-recessive&Disease.

References

  • Chapman AB, Devuyst O, Eckardt KU et al. Autosomal-dominant polycystic kidney disease (ADPKD): executive summary from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference. Kidney Int 2015;88(1):17-27. [PubMed]