How is autosomal recessive polycystic kidney disease differentiated from Wilms tumor on imaging?

Updated: Mar 04, 2019
  • Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR; Chief Editor: Eugene C Lin, MD  more...
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Answer

Answer

Autosomal recessive polycystic kidney disease, also known as infantile polycystic disease, is thought to result from dysplasia of the upper collecting system and/or collecting tubules, leading to cysts of various sizes. Microdissection studies have shown fusiform sacculations and cystic diverticula of the distal portions of collecting tubules and collecting ducts, while the proximal collecting tubules are diffusely dilated.

The condition is inherited in an autosomal recessive manner, and it is usually present in infancy or childhood, though it may be diagnosed in utero by means of ultrasonography. Disease severity is usually greatest in patients who present early.

Renal involvement is bilateral, but it may be asymmetric. Autosomal recessive polycystic kidney disease is associated with hepatic fibrosis and ductal hyperplasia, which may cause portal hypertension. In the context of this disease, death is usually caused by renal failure in the youngest children and by hepatic failure in older children.

The disease may be divided according to the patient's age at presentation, as follows:

  • Prenatal form: this form appears in infants, it is rapidly fatal, and it involves 90% of the renal tubules.

  • Infantile form: about 60% of the tubules are involved. The child has uremia but survives longer than those with the prenatal form.

  • Young-childhood form: Affected children present with hypertension and chronic renal failure. Approximately 25% of the renal tubules are involved.

  • Late presentation, juvenile form: symptoms are usually related to hepatic fibrosis, portal hypertension, and GI hemorrhage; in these late cases, small cysts are sometimes seen in the renal cortex.

Ultrasonography shows diffusely enlarged kidneys with a generalized increase in echoes produced by the innumerable fluid–tubular wall interfaces. The renal borders are poorly defined, and corticomedullary differentiation is lost. Echogenicity of the liver is frequently increased.

The peripheral cortex may be spared because it does not have collecting ducts. This feature is found in infants who do not have severe disease and who are likely to survive infancy. However, in severely affected infants, images may show a peripheral sonolucent halo, which may represent markedly dilated ectatic tubules near the renal surface. When high-resolution probes are used, imaging shows a radial array of ectatic and dilated tubules of 1-2 mm in diameter. In utero, the normal combined renal circumference is 27-30% of the abdominal circumference. In infantile polycystic disease, this circumference increases to 60%, a feature that allows for prenatal diagnosis.


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