cystic kidney diseases of childhood
The pediatric cystic renal diseases are a heterogeneous group of conditions defined by the presence of kidney cysts due to hereditary or non-hereditary causes:
- isolated simple cyst
- cystic renal dysplasia
- genetic disorders
- autosomal recessive polycystic kidney disease (ARPKD)
- autosomal dominant polycystic kidney disease (ADPKD)
- nephronophthisis-medullary cystic disease complex (NPH-MCKD)
- renal cysts and diabetes syndrome (RCAD) (HNF1B-associated disease, maturity-onset diabetes of the young type 5)
- Bardet-Biedl syndrome
- Joubert syndrome related disorders
- Jeune syndrome
- Meckel-Gruber syndrome
- tuberous sclerosis complex (TSC)
- Zellweger syndrome
- complex cystic tumors
- cystic nephroma and cystic partially differentiated nephroblastoma (CPDN)
- Wilms tumor (nephroblastoma)
- mesoblastic nephroma
- renal cell carcinoma
- acquired cystic kidney disease
Radiographic features
Ultrasound is the first-line modality for investigating kidney cysts, which appear as anechoic areas in the renal parenchyma .
Ultrasound of the liver and female internal genitalia is also recommended at first evaluation of cystic kidney disease to identify signs of associated pathology (liver cysts, hepatic fibrosis, portal hypertension, Müllerian duct anomalies) . If there is a concern for malignancy on finding complex cysts, contrast-enhanced MRI is recommended.
Radiology report
An international working group made the following suggestions for reporting investigations of pediatric cystic kidney disease .
- Size: The kidney should be measured using midsagittal length, as well as width and depth at the level of the hilum, which allows estimation of kidney volume by the prolate ellipsoid formula.
- Parenchyma: The renal parenchyma should be assessed by the cortical echogenicity (compared to the liver) and corticomedullary differentiation (normal, absent, or reversed), as very small cysts can solely manifest as increased echogenicity.
- Cysts: The presence of macroscopic cysts should be described by their number (1, 2-5, 6-10, or >10), side (unilateral or bilateral), location (cortical, medullary, corticomedullary border, ubiquitous), and size (maximal diameter of the largest cyst). Abnormal features suggestive of bleeding, infection, or malignancy should be documented, such as calcification, wall thickening, septations, echogenic debris, or hypervascularity of the septations or wall.
- Urinary tract: Urinary tract dilation should be identified, as it may be confused for cysts. Additionally, obstruction may be the cause of cystic renal dysplasia.
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