IS case 460: Cortical nephrocalcinosis

Keith Forrest Dockery, MD, MS

University of Rochester


Imaging Sciences URMC 2010
Publication Date: 2010-08-30

History

Patient is a 9-month-old female who initially presented at 3 month of age in the Emergency Department in acute renal failure, with severe acidemia, hyponatremia, and hyperkalemia, which lead to peritoneal dialysis. Now the patient presented with clinical question of renal dysplasia.

Findings

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Diagnosis

Cortical nephrocalcinosis

Discussion

Case discussion: The patient presented initially as a 3 month old with acute renal failure and severe metabolic derangement, including acidemia, hyponatremia, and hyperkalemia. Hyocalcemia was critical. Severity of the condition lead to peritoneal dialysis.

Ultrasound performed as routing evaluation found nonspecific increased echogenicity compatible with acute renal disease from a variety of causes. Primary consideration in an infant was given for autosomal recessive polycystic kidney disease (ARPKD).

On interval follow up imaging, the differential diagnosis favored cystic renal dysplasia, based on clinical and laboratory results. The patient was negative for genetic work-up for ARPKD.

Most recent imaging favored bilateral cortical nephrocalcinosis, with nonvisualization of renal parenchyma, compatible with end-stage renal disease, progressed from prior ultrasound. Consideration for etiology included: acute cortical necrosis, chronic glomerulonephritis, vitamin B6 deficiency, or less likely chronic hypercalcemia; prior work-up and history effectively eliminated Alport syndrome, poisoning, hyperoxaluria, transplant and sickle cell disease as other differentials.

Topic discussion: Two-thirds of nephrocalcinosis and nephrolithiasis are associated with underlying renal structural defect or infection. Approximately 10% are due to hypercalcemia or hypercalcuria. Approximately 20% are idiopathic.

Medical renal diseases include: autosomal recessive polycystic kidney disease (ARPKD) and nephrocalcinosis. Cortical nephrocalcinosis is seen as hyperechogenicity along the renal periphery and along the central septa of Bertin, with relative sparing of the medullary pyramids. Typically there is no shadowing.

Two types of ARPKD occur: a juvenile form wherein the liver predominates; and an infantile form wherein renal dysfunction predominates and renal cysts measure 1-2 mm, with ultrasound revealing diffuse echogenicity in cortex and medullary in enlarged kidneys. In the second type, juvenile ARPKD, hepatic fibrosis predominates with hepatosplenomegaly, and variable renal appearance.

In contrast, multicystic dysplastic kidney (MDK) typically presents as a “grape-like” collection of cysts of variable size that do not appear to communicate - cysts measure between 1 mm and 1 cm. MDK is typically unilateral, but can be bilateral in 20%. Failure to find cysts or echogenicity does not eliminated this disorder.

The most common causes of cortical nephrocalcinosis are chronic glomerulonephritis, acute cortical necrosis, and oxalosis. Acute cortical necrosis can be due to ethylene glycol, acute vascular insult, or methoxyflurane anesthesia. Other etiologies of nephrocalcinosis include: infections due to mycobacterium avium-intracellulare, cytomegalovirus, and pneumocystis carinii; Alport’s syndrome, an autosomal dominant hereditary nephritis (deafness and nephropathy).

Glomerulonephritis classically appears on ultrasound as diffusely hyperechoic (cortex greater than liver) with normal or enlarged size of kidneys. Prominent medullary pyramids. However, echogenicity should decrease over time. Ultrasound findings are nonspecific, with differential including: amyloidosis, nephrosclerosis, acute tubular necrosis, leukemia, Goodpasture’s syndrome, Henoch-Schönlein purpura, and nephritic syndrome. In chronic glomerulonephritis, the kidneys are small and diffusely echogenic with loss of corticomedullary differentiation, viz., findings are indistinguishable to end stage renal disease.

References

  1. Donnelly LF. Fundamentals of Pediatric Radiology. New York: WB Saunders Co. , 2001.
  2. Dunnick NR, Sandler CM, Newhouse JH, Amis ES. Textbook of Uroradiology, 3rd ed. New York: Lippincott Williams & Wilkins, 2001.
  3. Khan AN, MacDonald S, Chandramohan M, Chandramohan H. Nephrocalcinosis. eMedicine. Updated July 10, 2008. http://emedicine.medscape.com/article/379449-overview
  4. Rumack CM, Wilson SR, Charboneau JW. Diagnostic Ultrasound, 3rd ed. Mosby, Inc, 2005.

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