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Acquired Cystic Kidney Disease

Definition

Acquired cystic kidney disease (ACKD) is characterized by the development of multiple bilateral cysts in the kidneys of patients with chronic kidney disease without a history of a hereditary cystic disease (Choyke et al., 2000).

Epidemiology:

The prevalence of acquired cystic kidney disease depends strongly on the duration of end-stage renal disease, the time on dialysis, the imaging modality used, and the diagnostic criteria: from about 10% (less than 1 year on dialysis) to more than 90 % (more than 10 years on dialysis).

Etiology of Acquired Cystic Kidney Disease

Tubular obstruction caused by fibrosis, oxalate crystals, or vascular occlusions leads to renal cysts. Secondly, cystogenic and/or carcinogenic substances of uremia (e.g., lack of elimination of growth factors) are responsible. The development of renal cysts correlates with the duration of end-stage renal disease; renal transplantation improves ACKD. After graft failure, the activity of ACKD increases again and may also affect the kidney transplant. There is an increased risk of malignancy; up to 1% develop a renal cell carcinoma.

Pathology

Gross pathology:

Bilateral cortical cysts, on average 0.5 to 1 cm in size. Calcium oxalate crystals are often found in the cysts.

Risk of malignancy:

Adenomas, atypical epithelial proliferations, and renal cell carcinoma may occur in the shrunken kidneys. Findings suspicious for a tumor include newly appearing solid or contrast-enhancing lesions, interval growth, hemorrhage, or complex cystic morphology.

Renal cell carcinoma arising in acquired cystic kidney disease is regarded as a distinct subtype in the WHO classification (acquired cystic disease-associated renal cell carcinoma, ACD-RCC). In contrast to the classic RCC subtypes, ACD-RCC typically shows a mixed microcystic-cribriform, tubular, and papillary morphology with eosinophilic tumor cells and intratumoral calcium oxalate crystals in patients with ARCD.

Signs and Symptoms

Acquired cystic kidney disease is often asymptomatic and is detected incidentally on imaging. Clinically relevant manifestations include Flank pain, hematuria, cyst hemorrhage, rarely retroperitoneal hemorrhage, cyst infection, and the detection of a suspicious renal mass.

Diagnosis of Acquired Cystic Kidney Disease

Renal Ultrasound Imaging:

Renal ultrasound imaging shows small kidneys with multiple cysts. Signs of a cyst infection are a thickened cyst wall and hyperechogenic cysts. Renal tumors may be visible.

Abdominal CT Scan or MRI:

Indicate CT scan or MRI imaging if suspicious cysts are seen in ultrasound imaging. Prefer MRI imaging in patients with chronic kidney disease without dialysis.

Differential Diagnosis

Important differential diagnoses include autosomal dominant polycystic kidney disease (ADPKD), other hereditary cystic kidney diseases, simple renal cysts in chronic kidney insufficiency, and cystic renal tumors. Findings arguing against ADPKD include the typically small rather than enlarged kidneys, the absence of a corresponding family history, and the lack of typical extrarenal manifestations.

Treatment of acquired cystic kidney disease

Asymptomatic acquired cystic kidney disease does not require causal therapy. Treatment is directed at complications such as hemorrhage, infection, or suspected malignancy.

Infected cyst:

Initial treatment is with antibiotics. If antibiotic therapy fails, percutaneous drainage or, rarely, nephrectomy may be indicated in cases of a large infected cyst, abscess formation, or a severe septic course.

In bleeding or hematuria:

In addition to supportive measures and adjustment of anticoagulation, angiographic embolization or, in exceptional cases, nephrectomy may be required in the setting of significant bleeding.

Screening for renal tumors:

There is no uniformly accepted screening protocol for asymptomatic dialysis patients with regard to acquired cystic kidney disease or renal tumors. In clinical practice, serial ultrasonographic follow-up of the native kidneys is performed as a minimal recommendation in patients on long-term dialysis. Alternatively, annual CT or MRI may be considered in patients with a good life expectancy or those on the waiting list for kidney transplantation.

In suspected malignancy:

The standard treatment for nonfunctioning native kidneys is radical nephrectomy. Active surveillance may be considered in selected individual cases with a small lesion, high surgical risk, or limited life expectancy. Nephron-sparing approaches are an option only in patients with compensated renal insufficiency.

References

Choyke 2000 CHOYKE, P. L.: Acquired cystic kidney disease.
In: Eur Radiol
10 (2000), Nr. 11, S. 1716–21

  German version: Erworbene zystische Nierenerkrankung

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