eMedicine Specialties > Urology > Congenital Urologic Conditions

Cystic Diseases of the Kidney: Follow-up

Author: Andrew T Trout, MD, Resident, Department of Radiology, University of Michigan
Coauthor(s): Justin A Siegal, MD, Radiologist, Department of Radiology, Virginia Mason Medical Center; John M Corman, MD, Clinical Associate Professor of Urology, University of Washington at Seattle; Consulting Staff, Department of Urology, Virginia Mason Medical Center
Contributor Information and Disclosures

Updated: Jul 22, 2009

Follow-up

Further Outpatient Care

• Developmental cystic renal disease: Patients with multicystic dysplastic kidney should be observed with periodic sonography to monitor for neoplastic changes.
• Inherited cystic renal disease: Patients with autosomal dominant polycystic kidney disease (ADPKD) should be screened for intracranial saccular aneurysms with magnetic resonance angiography (MRA) or another imaging modality.
• Systemic disease with associated renal cysts
• Acquired renal cystic disease (ARCD): Screen patients with chronic renal failure for acquired cystic disease because of the associated risk of renal cell carcinoma (RCC). Initial ultrasound or CT scan screening may be performed after 3 years of dialysis and is repeated every 1-2 years thereafter. In patients with ARCD, contrast-enhanced CT scan can be performed annually to screen for carcinoma. This screening may be most valuable in younger patients and in patients with large cysts.
• Medullary sponge kidney (MSK): Regular follow-up care with sonography and urinalysis is recommended to monitor for calculi or infection.
• Simple, intermediate, and suspicious renal cysts: If the CT identification of a simple cyst is equivocal, observe the cyst with repeat scans. For Bosniak category IIF lesions, perform contrast-enhanced renal CT scan studies in 6 months and annually thereafter for at least 5 years.
• Some experts suggest that patients with Bosniak category II lesions require no follow-up. However, the data are confusing because reported larger cases series did not separate category IIF from category II lesions. Thus, these series report malignancy rates of up to 14% for category II lesions. Given these rates, some physicians also choose to follow up with patients with category II lesions (treating them as IIF lesions).
• Systemic disease with associated renal cysts
• Tuberous sclerosis (TS): Screen patients with periodic CT scan or sonography to monitor for carcinoma development. A noncystic mass that lacks the fat of a typical angiomyolipoma or an enlarging cyst may suggest carcinoma.
• Von Hippel-Lindau syndrome (VHLS): Perform renal sonography annually to monitor cyst or other mass development. In patients with multiple cysts, perform CT scan or MRI every 1-3 years to monitor for RCC.
• Acquired cystic renal disease
• Acquired renal cystic disease (ARCD): The value of screening patients with chronic renal failure for the development of acquired cystic disease is debated. Some advocate screening because of the associated risk of RCC. Decision analyses have demonstrated that screening is valuable only in patients with a life expectancy of more than 25 years. Thus, in the United States, screening is limited to patients who have been on dialysis for more than 5 years, have extended expected survival, and are showing signs of acquired cystic renal disease.⁵ Ultrasonography or CT scan should be used for initial screening and repeated every 1-2 years thereafter. In patients with known ARCD, contrast-enhanced CT scan can be performed annually to screen for carcinoma.
• MSK: Regular follow-up care with sonography and urinalysis is recommended to monitor for development of calculi or infection.
• Simple, intermediate, and suspicious renal cysts: If the CT identification of a simple cyst is equivocal, observe the cyst with repeat scans. For Bosniak category IIF lesions, perform contrast-enhanced renal CT scan studies in 6 months and annually thereafter for at least 5 years.
• Some experts suggest that patients with Bosniak category II lesions require no follow-up. However, the data are confusing because reported larger cases series did not separate category IIF from category II lesions. Thus, these series report malignancy rates of up to 14% for category II lesions. Given these rates, some physicians also choose to follow up with patients with category II lesions (treating them as IIF lesions).

Complications

• Developmental cystic renal disease: Concerns in patients with multicystic dysplastic kidney (MCDK) include cyst rupture, infection, calcification, and malignancy.
• Inherited cystic renal disease: If a patient experiences persistent pain, consider the possibility of renal infection, tumor, or nephrolithiasis. Ten to 20% of patients have urate or calcium oxalate nephrolithiasis. One third to one half of patients experience renal infection, including infected cyst and pyelonephritis (women are affected more frequently than men). Perinephric extension with abscess is a potential sequela and has a 60% mortality rate. Reports suggest increased rates of RCC, with carcinoma developing in 1-5% of patients with ADPKD. Berry aneurysms often are stressed by concomitant hypertension, and they bleed in 5-10% of patients.
• Systemic disease with associated renal cysts
• TS: RCC occurs in a small percent of patients with TS (<5%).
• VHLS: Seventy percent of patients with VHLS who survive to age 60 years develop RCC. The tumor is frequently bilateral and multicentric.
• Acquired cystic renal disease
• ARCD: This condition is associated with RCC, although a causal relationship has not been established. The incidence of RCC is 30 times greater in people with ARCD than in the general population, 4-7% over a 7- to 10-year period. Notably, this rate is much higher in men than women (male-to-female ratio, 7:1) and in patients with cysts enlarging the kidney outside the normal range. Patients may also have cyst rupture and hemorrhage, although fewer than 14% of patients experience episodes of hematuria. With cyst rupture, hemorrhage into the pelvis or retroperitoneum can occur.
• MSK: Nephrolithiasis and nephrocalcinosis are common in patients with MSK. MSK is found in 8.5-20% of patients with nephrolithiasis. The dilated collecting ducts may have relatively diminished flow, favoring calcium deposition. Other common complications of this disease include renal infection and hematuria. A rare complication is renal abscess, which requires a prolonged course of antibiotics and possible surgical drainage.
• Simple cyst: A simple cyst can become either hemorrhagic or infected. The cause of the hemorrhage is often unclear, but it may be related to trauma, bleeding diatheses, or varices in the cyst wall. Infected cysts may be due to a disseminated hematogenous infection, ascending UTI, or urologic instrumentation.

Prognosis

• Developmental cystic renal disease: If bilateral, MCDK is incompatible with life. More typically, the disease is unilateral or segmental and is discovered on prenatal sonogram.
• Inherited cystic renal disease
  • ADPKD: Renal insufficiency typically develops in people older than 30 years, and 45% of patients progress to end-stage renal failure by the age of 60 years. One third of patients die secondary to renal failure, one third die due to complications from hypertensive nephropathy (HTN), and 6-10% die secondary to subarachnoid hemorrhage.
  • Autosomal recessive polycystic kidney disease (ARPKD): Neonates presenting with ARPKD often die within 6 weeks secondary to pulmonary disease and renal failure. If patients survive this first period, they have an 80% chance of living to 15 years. For patients presenting in infancy, approximately one third progress to severe renal insufficiency at age 5 years and nearly 100% progress by age 20 years.
  • Juvenile nephronophthisis (JNPHP) and medullary cystic kidney disease (MCKD): Patients typically progress to renal failure within 5-10 years of presentation.
• Systemic disease with associated renal cysts: As many as 40% of patients with VHLS develop RCC, which is the leading cause of death.
• Acquired cystic renal disease
  • Acquired cystic renal disease is progressive while the patient remains on dialysis. The disease often regresses after transplantation, but associated tumors may become more aggressive because of the patient's immunosuppression.⁵
  • MSK carries an excellent prognosis and is typically nonprogressive.

Patient Education

• Inherited cystic renal disease: Genetic counseling is important in all of the heritable diseases. Individuals with autosomal dominantly inherited diseases (eg, ADPKD) need to be counseled that their offspring have a 50% chance of developing the disease. Those with autosomal recessively inherited diseases (eg, ARPKD) should be counseled that all of their offspring will carry the disease. Parents of children with an autosomal recessively inherited disease should be counseled that subsequent children have a 25% chance of having the disease and a 50% chance of being an unaffected carrier of the gene.
• For excellent patient education resources, visit eMedicine's Kidneys and Urinary System Center. Also, see eMedicine's patient education article Blood in the Urine.

Miscellaneous

Medicolegal Pitfalls

• The Bosniak classification system greatly varies from observer to observer, particularly in the differentiation of Bosniak category II from Bosniak category III lesions. Additionally, a significant portion of Bosniak category II lesions may prove to be malignant. In one series, 14% of lesions so categorized were found to be malignant. Thus, adherence to classification standards and recommended follow-up care, particularly for Bosniak category IIF, should be strictly followed.

Special Concerns

• Avoid instrumentation of the lower urinary tract in patients with cystic renal diseases who have increased susceptibility to infection (ie, with autosomal dominant polycystic kidney disease [ADPKD], autosomal recessive polycystic kidney disease [ARPKD], medullary sponge kidney [MSK]).

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