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Kidney tumor - cysts, children, adult benign

Cystic non-neoplastic lesions

Cystic renal dysplasia

Reviewers: Mandolin Ziadie, M.D. (see Reviewers page)
Revised: 22 December 2011, last major update December 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.


● Congenital cystic anomaly of the kidney caused by abnormal metanephric differentiation, occurring by week 20 in utero
● Enlarged, cystic kidneys with disorganized parenchyma and numerous cysts
● Immature tubules surrounded by mesenchymal collars and islands of immature mesenchyme are present between the cysts
● Also known as multicystic renal dysplasia


● Most common pediatric cystic renal disease
● Most often a sporadic event but familial cases have been reported
● 90% are associated with ureteropelvic obstruction, ureteral agenesis, atresia or reflux; 10% have unknown cause
● Bilateral disease should raise the suspicion of occult disease in parents
● Also associated with cardiac malformations, Meckel-Gruber syndrome (eMedicine), inherited metabolic abnormalities (Pediatr Nephrol 2007;22:2119), thanatophoric dysplasia type 1 (Genet Couns 2006;17:407) and other familial syndromes (Am J Med Genet 1996;63:332)

Clinical features

● Most common cause of neonatal abdominal masses; presents as flank mass or pyelonephritis
● In bilateral disease, neonates may also display oligohydramnios and pulmonary hypoplasia
● If blastema present, patient is at a slightly higher risk for Wilms’ tumor
● Segmental dysplasia is seen in children with duplex (duplicated) kidney (incomplete fusion of upper and lower poles)

Case reports

● Newborn with bilateral renal dysplasia, severe pancreatic fibrosis, intrahepatic biliary dysgenesis and total situs inversus with normal cytogenetics (Hum Pathol 1988;19:871)

Gross description

● Enlarged kidney distorted by variably sized cysts that may involve one or both (20%) kidneys
● Indistinct cortico-medullary junction
● Usually associated with ureteropelvic obstruction or ureteral atrophy / atresia

Gross images


Multiple cysts of various sizes

Multiple cysts of various sizes #5

With small bladder

Cysts are smooth lined, no normal kidney tissue is apparent

Due to congenital urethral stenosis with hypertrophic bladder wall and bladder diverticulum

With ipsilateral hypoplasia of ureter

Micro description

● Disorganized parenchyma that is distorted by cysts of various sizes, lined by flattened to cuboidal epithelium
● May contain nodular blastema (undifferentiated cells), islands of undifferentiated mesenchyme, cartilage (10-20%), immature collecting ducts with fibromuscular collars and primitive glomerular structures

Micro images

Large cysts lined by flattened epithelium with fibrotic and cartilaginous stroma

Irregular cysts with occasional intervening tubules and glomeruli

Islands of cartilage in stroma

Multiple small cysts and immature tubules, surrounded by immature connective tissue with abortive glomerular structures

Immature mesenchyme and cysts #1, #2

Differential diagnosis

Autosomal dominant polycystic kidney disease: familial, adults, rarely presents at birth; alterations in PKD1, PDK2 or PKD3
Autosomal recessive polycystic kidney disease: familial, uniform cysts in neonates, cysts are radially arranged, no immature mesenchyme or cartilage; abnormalities in PKHD1 gene
Cystic nephroma: sharply demarcated from adjacent kidney by thick fibrous capsule, no renal tissue between cysts, no immature mesenchyme or cartilage
Cystic partially differentiated nephroblastoma: epithelial and stromal elements and nephroblastomatous tissue; usually hyperdiploid with trisomy 12

Additional references

eMedicine #1; #2

End of Kidney tumor - cysts, children, adult benign > Cystic non-neoplastic lesions > Cystic renal dysplasia

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