Embryology · Urogenital system
Multicystic dysplastic kidney and polycystic kidney disease !
- Malformation
Kidneys full of cysts for two different reasons: a kidney that never formed properly, or a genetic defect of the tubule cells.
Updated 2026-11-01
See it in 3D: Kidneys
What it is
A multicystic dysplastic kidney never developed because the dialogue between ureteric bud and blastema failed: what remains is a non-functioning cluster of cysts, almost always on one side. Polycystic kidney disease is inherited: the autosomal recessive form shows at birth and the dominant form in adulthood. Telling them apart on prenatal ultrasound changes the outlook completely.
Embryological cause
- Multicystic dysplastic: the ureteric bud fails (often with ureteral atresia) and does not induce normal nephrons; the blastema forms cysts and dysplastic tissue.
- It is linked to disturbances of the GDNF–RET pathway that guides bud branching.
- Polycystic: nephrons form, but a defect in primary cilium proteins (polycystins, fibrocystin) disturbs proliferation and secretion of the tubular epithelium.
- In the recessive form the collecting ducts dilate radially; in the dominant form cysts arise from any nephron segment and grow over the years.
Markers
- PKD1
- PKD2
- PKHD1
- GDNF
- RET
How it presents
- Multicystic: an abdominal mass in the newborn or a prenatal finding; many involute over time.
- Recessive: oligohydramnios, pulmonary hypoplasia, palpable kidneys, hypertension and early renal failure; portal hypertension from hepatic fibrosis.
- Dominant: flank pain, haematuria, hypertension, infections, stones and progression to chronic kidney disease.
- Dominant: liver cysts, mitral valve prolapse and intracranial aneurysms.
Diagnosis
- Prenatal ultrasound: large non-communicating cysts without normal parenchyma (multicystic) versus enlarged, hyperechoic kidneys (recessive).
- Renal scintigraphy: the multicystic kidney shows no uptake.
- Ultrasound and cystography of the other kidney in multicystic disease.
- Genetic testing and ultrasound of relatives for the dominant form.
Test yourself
Think of the answer, then tap the question to see it.
What is the embryological cause of a multicystic dysplastic kidney?
Failure of the ureteric bud, often with ureteral atresia, so normal nephrons are not induced; the blastema forms cysts and dysplastic tissue.
Which gene is altered in autosomal recessive PKD, and which liver lesion goes with it?
PKHD1 (fibrocystin); it goes with congenital hepatic fibrosis.
What are the extrarenal complications of autosomal dominant PKD?
Liver cysts, intracranial aneurysms and mitral valve prolapse, among others.
Why is the other kidney examined in a child with a multicystic kidney?
It often has vesicoureteral reflux or UPJ obstruction, and it is the only working kidney.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- Kidney: pronephros, mesonephros, metanephros and ascent
- Renal agenesis and the Potter sequence
- Duplicated ureter, UPJ obstruction and posterior urethral valves
- Amniotic fluid: polyhydramnios and oligohydramnios
- Pulmonary hypoplasia
- Biliary atresia
Related conditions
Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given.
Sources: Polycystic kidney disease: MedlinePlus Genetics (MedlinePlus, U.S. National Library of Medicine, 2024); Embryology, Kidney, Bladder, and Ureter - StatPearls - NCBI Bookshelf (StatPearls Publishing (NCBI Bookshelf), 2023); Embryology, Genitourinary - StatPearls - NCBI Bookshelf (StatPearls Publishing (NCBI Bookshelf), 2023).
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Representative model, for educational purposes only.