Multicystic Dysplastic Kidney (MDCK) is a non-heritable developmental disorder where the kidney is replaced by non-functioning cysts. It is usually unilateral and asymptomatic, though it can present as an abdominal mass. Imaging such as ultrasound is used for diagnosis and shows cysts of varying sizes replacing normal renal architecture with no communication between cysts. Treatment involves follow up monitoring, with nephrectomy in some cases of hypertension or massive enlargement. Differential diagnosis includes other cystic kidney diseases and tumors.

1. Multicystic Dysplastic Kidney
Dr Musa W. A.
Registrar, FMCK
24th August, 2023
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2. Outline
• Introduction
• Epidemiology
• Aetiopathology
• Clinical Features
• Radiologic Features
• Treatment
• Differential Diagnosis
• Conclusion
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3. Introduction
• Multicystic Dysplastic Kidney (MDCK) is a type of non-heritable
developmental disorder in which the kidney is replaced by non-
functioning non-communicating cysts.
• It is the most common form of cystic disease in infants.
• Usually unilateral, asymptomatic or present as abdominal mass.
• Can be diagnosed in-utero or in neonate through USS.
• If unilateral, chances of complete resolution in 60%.
• Bilateral disease is fatal.
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4. Epidemiology
• Most common form of cystic disease in infants.
• 2nd most common cause of an abdominal mass in neonate (after
hydronephrosis).
• Unilateral incidence is estimated at 1:2500-4000.
• Prevalence: 1:4,300 (for unilateral MCDK), 1:10,000 (for bilateral MCDK) LB
• M:F = 2:1 (for unilateral MCDK).
• More common among infants of diabetic mothers.
• Risk of recurrence: 2–3%
• Genetics: sporadic NOT familial .Rarely autosomal dominant forms are seen
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5. Aetiopathology
• Aetiology is said to be due to obstruction / atresia of ureter during
metanephric stage before 8–10 weeks GA.
• This inhibits nephron development – as a result the collecting tubules
enlarge into cysts with the formation of immature glomeruli and
tubules.
• Hence, the affected kidney (or renal segment) has no functioning
renal tissue and is replaced by multiple cysts.
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6. Aetiopathology
• Location
1. Unilateral
• Most common form (80–90%); L:R = 2:1
• Caused by pelvoinfundibular atresia.
• In 33% associated with contralateral kidney abnormal: VUR, PUJO, Horseshoe
kidney, Ureteral anomalies, Renal hypoplasia, Megaloureter, Malrotation,
Renal agenesis.
• Also associated with anomalies of the ipsilateral kidney: VUR, Ectopic ureter
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7. Aetiopathology
• Location
2. Segmental / Focal renal dysplasia
• “Multilocular cyst” secondary to:
- High-grade obstruction of upper pole moiety in duplex kidney from ectopic
ureterocoele
- Single obstructed infundibulum
3. Bilateral cystic dysplasia
• In the presence of severe obstruction in utero from PUV / urethra atresia
• With oligohydramnios + pulmonary hypoplasia
• Prognosis: lethal
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8. Aetiopathology
• Potter Types
1. Multicystic kidney (Potter IIa)
• Large kidney with multiple large cysts + little visible renal parenchyma
2. Hypoplastic / diminutive form (Potter IIb)
• Echogenic small kidney
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9. Aetiopathology
• Time of appearance:
A. Related to Site of Obstruction
• Ureteropelvic junction: single / several large / multiple medium-sized cysts in
large kidney
• Distal ureter / urethra: small / no cysts in small kidney
B. Related to Time of Insult
• Early onset between 8th and 11th week
- Small / atretic renal pelvis + calices
- 10–20 cysts + loss of reniform appearance
• Late onset = Hydronephrotic Form
- Large central cyst (= dilated pelvis) often communicating with cysts
- Some renal function may be demonstrated
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10. Clinical Features
• Asymptomatic if unilateral (may go undetected until adulthood).
• Abdominal mass.
• Recurrent urinary tract infections, intermittent abdominal pain,
nausea + vomiting, haematuria, failure to thrive.
• Fatal form: bilateral MCDK (4.5–21%), contralateral renal agenesis (0–
11%).
• Pulmonary hypoplasia if bilateral → fatal
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11. Radiologic Features
• Best described using the following imaging modalities:
- Ultrasonography
- MRI
- Nuclear Medicine
- Radiography (Plain/ Contrast Study)
- Angiography
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12. Radiologic Features - Ultrasonography
• It is the preferred initial examination.
• Prenatal USS has been shown to have a diagnostic accuracy of > 90%.
• Can provides clues of other urinary tract anomalies.
• Findings:
- Normal renal architecture replaced by:
• Random cysts of varying shape + size (“cluster of grapes”) with largest cyst in periphery
→ lobulated renal contour.
• Non-medial location (100% accurate)
• Cysts separated by septa (100% accurate)
• No communication between multiple cysts (93% accurate)
• Cysts begin to disappear in infancy.
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13. Radiologic Features - Ultrasonography
• Findings(contd.)
- Central sinus complex absent (100% accurate).
- No identification of parenchymal rim or corticomedullary differentiation (74%
accurate).
- Hypoplastic and echogenic atophic kidney (Potter IIb).
- Hydronephrotic form
- Oligohydramnios in bilateral MCDK / unilateral MCDK + contralateral urinary
obstruction with absence of a visible bladder.
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19. Radiologic Features - MRI
• The non-ionizing radiation imaging modality is an important
consideration in the paediatric population.
• MCDK cysts are eloquently demonstrated on T2 sequences – seen as
multiple non-communicating hyperintense structures.
• It show the typical multicystic appearance of MCDK with little or no
renal parenchyma.
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22. Radiologic Features – Nuclear Medicine
• NUC preferred over IVP in first month of life as concentrating ability of
even normal neonatal kidneys is suboptimal.
• Help differentiates between MCDK & hydronephrosis ( mild & mod.)
• Uses the radiotracer 99mTc-MAG 3 or DTPA.
• Finding:
- Generally, no function/uptake seen in the renal bed of the affected side.
- May show some flow to the kidney and possible cortical uptake
- Excretion is never seen.
• DDx: severe hydronephrosis (peripheral activity), PUJ obstruction
(minimal uptake)
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24. Radiologic Features – Radiography
• Incidental findings on kidney, ureter, and bladder (KUB) images
include displacement of the bowels when the affected kidney is
enlarged.
• Also, ringlike calcifications of the cyst walls may be seen on plain
images.
• Retrograde pyelography may demonstrate an atretic or absent ureter.
• VCUG may be indicated in pxs with MCDK to evaluate the urinary
tract for VUR and other anomalies, including an ipsilateral
ureterocoele.
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26. Radiologic Features – Angiography
• It shows absent / hypoplastic renal artery;
• Angiography not usually necessary since a DDx to long-standing
functionless kidney is not possible
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27. Treatment
• OB management:
- Routine antenatal care + evaluation by paediatric urologist following delivery if
unilateral
- Option of pregnancy termination if ≤ 24 weeks GA
- Non-intervention for foetal distress if > 24 weeks GA
• Complications
- Renin-dependent hypertension (rare)
- Malignancy in < 1:330
• Treatment:
- Follow-up in 3–4month intervals in first year (isolated reports of developing
malignancy)
- Nephrectomy (in hypertension / massive renal enlargement)
- Assessment of contralateral kidney for VUR
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28. Differential Diagnosis
• Cystic renal dysplasia
• multicystic dysplastic kidney (MCDK)
• obstructive 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)
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• Bardet-Biedl syndrome
• Joubert syndrome related disorders
• Jeune syndrome
• Meckel-Gruber syndrome
• Tuberous sclerosis complex (TSC)
• Zellweger syndrome
•Complex cystic tumours
• Cystic nephroma and cystic partially
differentiated nephroblastoma (CPDN)
• Wilms tumour (nephroblastoma)
• Mesoblastic nephroma
• Renal cell carcinoma
•Acquired cystic kidney disease
•Isolated simple cyst

29. Differential Diagnosis – Obstructive Cystic
Renal Dysplasia
• Potter type IV cystic renal disease
• Kidneys are usually normal to
small
• Highly echogenic cortices, loss of
cortico-medullary differentiation,
and scattered cysts (usually
smaller than those seen with
MCDK).
• The reniform shape is often
preserved until late in the
disease.
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30. Differential Diagnosis – ARPKD
• Potter type I cystic renal disease.
• Inherited
• Numerous cylindrical cysts in the
cortex and medulla on high
resolution probe.
• Initially cysts too small to resolve
• Affects both kidneys with
associated hepatic fibrosis
• kidneys appear enlarged and
echogenic but usually, retain a
reniform shape.
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31. Differential Diagnosis – ADPKD
• Potter type III.
• Inherited
• Usually present in adulthood –
normal kidney at birth.
• Affects both kidneys +/- cysts in
liver, spleen, pancreas, ovaries
and seminal vesicles.
• Usual appearance as multiple
simple cysts of varying sizes and
shades in the cortex and medulla
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32. Differential Diagnosis – Paediatric cystic
nephroma
• Unifocal multiloculated cystic
masses surrounded by a thick
fibrous capsule and compressed
parenchyma.
• Claw or beak-shape of adjacent
renal parenchyma (claw sign).
• Cyst contents are usually
anechoic, but low-level echoes
may be seen.
• Septal vascularity can also be
seen.
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33. Differential Diagnosis
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34. Conclusion
• MDCK is the most common cystic kidney diseased in neonate of
which prenatal USS plays a significant role in its early diagnosis.
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35. Reference
• Dahnert W(2017). Radiology Review Manual. 8th ed. Philadelphia:
Wolters Kluwer. Pg 3125 – 3127.
• David Sutton (2003). Textbook of Radiology and Imaging. 7th ed. Pg
1060.
• Lee Alexander Grant, Nyree Griffin, (2013). Grainger & Allison's
Diagnostic Radiology Essentials. Pg 484 – 485.
• Gaillard F, Habana J, Malik A, et al. Multicystic dysplastic kidney.
Reference article, Radiopaedia.org (Accessed on 23 Aug 2023)
https://doi.org/10.53347/rID-1695
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