Diagnostic Ultrasound - Abdomen and Pelvis

Cystic Disease of Dialysis
Diagnoses: Urinary Tract
• Cerebral paraventricular calcifications
Medullary Cystic Disease
• Rare disease associated with progressive salt wasting
nephropathy, renal insufficiency
• Cysts may be too small to be seen; visible cysts occur only in
medulla
• Kidneys are almost invariably small in size
• Clinically, progressive renal failure in young patients
PATHOLOGY
General Features
• Etiology
○ Destruction of functional renal tissue, with
compensatory hypertrophy of normal nephrons
○ Proliferation of epithelial cells from proximal renal
tubules
– Increased circulating growth factors and protooncogene
activation
○ Fluid accumulation and expansion of renal tubule leads
to cyst formation
– Obstruction of tubules by oxalate crystals, interstitial
fibrosis, or hyperplasia
– Altered compliance of tubular basement membrane
– Eventually loses connection with parent tubule to
become isolated sac
Gross Pathologic & Surgical Features
• Atrophic kidneys with multiple small cysts, renal cortex >
medulla, containing clear fluid or hemorrhage
Microscopic Features
• Cysts lined by single layer of flattened or cuboidal
epithelium
• Papillary projections from cyst wall are common
• Calcium oxalate deposition in cyst walls
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Most patients with ACKD are asymptomatic
○ History of chronic renal failure and long-term dialysis
• Other signs/symptoms
○ Hematuria, flank pain, fever if complications occur
Demographics
• Gender
○ M > F ~ 3:1
• Epidemiology
○ Prevalence of ACKD in dialysis patients
– 10-20% after 3 years
– 40-60% after 5 years
– > 90% after 10 years
○ Can be seen in up to 13% of patients with CKD prior to
dialysis
○ Equal incidence in hemodialysis and peritoneal dialysis
Natural History & Prognosis
• Size and number of cysts correlate with duration of dialysis
but not with renal disease
• Complications
○ Intracystic hemorrhage in up to 50% of patients
○ Cyst infection
○ Rupture with retroperitoneal hemorrhage (13% of
patients)
○ Renal stones
• Malignant transformation to RCC
○ Develops in up to 7% of patients with ACKD over period
of 7-10 years
○ Less aggressive than classical RCC, more commonly
papillary RCC with infrequent metastasis (5-7%)
– Acquired cystic disease associated RCC: New subtype
exclusive to ACKD and long term dialysis
○ Risk of is higher in patients with cysts enlarging the renal
volume
• Prognosis: In absence of RCC, dependent upon course of
underlying renal disease
Treatment
• Asymptomatic simple and complex cysts require no
treatment
• Bleeding and rupture usually treated conservatively
• Painful cysts may require drainage
• Infected cysts may require antibiotics and drainage
• Persistent and severe hemorrhage necessitates
nephrectomy or renal artery embolization
• Bosniak category III and IV cysts require surgical exploration
and nephrectomy
○ ~ 50% of category III cysts are malignant (RCC)
• Renal transplantation prevents formation of new cysts but
does not decrease malignant potential of existing cysts
○ Prevents formation of new cysts; existing cysts may
regress
○ Malignant potential may increase as result of
immunosuppression
DIAGNOSTIC CHECKLIST
Consider
• Correlate with history to exclude hereditary cystic disease
• CT or US screening of asymptomatic patients for RCC and
ACKD
Image Interpretation Pearls
• Bilateral, multiple small cysts in small to normal-sized
echogenic kidneys
• Differentiate hemorrhagic cysts from small RCC
SELECTED REFERENCES
1. Wood CG 3rd et al: CT and MR Imaging for Evaluation of Cystic Renal Lesions
and Diseases. Radiographics. 35(1):125-41, 2015
2. Cokkinos DD et al: Contrast enhanced ultrasound of the kidneys: what is it
capable of? Biomed Res Int. 2013:595873, 2013
3. Singanamala S et al: Should screening for acquired cystic disease and renal
malignancy be undertaken in dialysis patients? Semin Dial. 24(4):365-6, 2011
4. Katabathina VS et al: Adult renal cystic disease: a genetic, biological, and
developmental primer. Radiographics. 30(6):1509-23, 2010
5. Ishikawa I et al: Twenty-year follow-up of acquired renal cystic disease. Clin
Nephrol. 59(3):153-9, 2003
6. Nascimento AB et al: Rapid MR imaging detection of renal cysts: age-based
standards. Radiology. 221(3):628-32, 2001
7. Choyke PL: Acquired cystic kidney disease. Eur Radiol. 10:1716-1721, 2000.
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