Autosomal recessive polycystic kidney disease
Summary
Congenital ciliopathy due to PKHD1 (fibrocystin) causing enlarged echogenic kidneys with tiny collecting-duct cysts and congenital hepatic fibrosis → major cause of renal failure in infancy/childhood.
Genetics & pathophysiology
- Inheritance: autosomal recessive.
- Gene: PKHD1 (fibrocystin/polyductin) – expressed in renal collecting ducts and bile ducts.
- Key pathology:
- Fusiform dilatation of collecting ducts → “microcystic” kidneys.
- Ductal plate malformation in liver → congenital hepatic fibrosis ± Caroli-like changes.
Clinical features
- Spectrum:
- Perinatal/infantile: severe renal enlargement, oligohydramnios, pulmonary hypoplasia, early death.
- Childhood/juvenile: slower renal decline, portal hypertension from hepatic fibrosis.
- Presentation:
- Palpable abdominal masses (enlarged kidneys).
- Renal failure (polyuria, polydipsia, growth failure).
- Portal HTN: splenomegaly, varices, hypersplenism.
Imaging - kidney
- Prenatal US
- Bilaterally enlarged, uniformly echogenic kidneys.
- Poor corticomedullary differentiation.
- No discrete macrocysts, may see oligohydramnios.
- Postnatal US
- Kidneys large, echogenic, smooth outline.
- Loss of corticomedullary differentiation.
- May see tiny cortical/medullary microcysts on high-res US.
- CT/MRI
- Diffusely enlarged kidneys with fine, radially oriented microcysts.
- Used mainly to assess liver/biliary tree rather than kidneys alone.
Imaging - liver
- US/MRCP:
- Congenital hepatic fibrosis: coarse liver, periportal echogenicity.
- Dilated intrahepatic bile ducts (Caroli-like changes).
- Stigmata of portal HTN: splenomegaly, collaterals.
Exam angle
Think ARPKD in a neonate with oligohydramnios, huge echogenic kidneys, respiratory distress, and later portal hypertension from congenital hepatic fibrosis.
