Case of the Month: July 2008

Diagnosis

  • Renal Infarction.

Discussion

Renal infarction is the formation of a coagulated, necrotic area in one or both kidneys that results from renal blood vessel occlusion. The size and location of the infarct depend on the site of vascular occlusion. Most often, infarction affects the renal cortex, but it can extend into the medulla. Residual renal function after infarction depends on the extent of the damage.

Causes

  • Embolism: Cardiac (most common)
    • Rheumatic, arrhythmias, myocardial infarction, prosthetic valve.

  • Thrombosis
    • Atherosclerosis, polyarteritis nodosa

    • Aneurysm or dissection (aorta/renal artery)

    • Sickle cell disease, thrombotic thrombocytopenic purpura, thromboangiitis obliterans

  • Trauma
    • Blunt or penetrating

    • Surgery, interventional procedures

Imaging

  • Best diagnostic clue: Nonenhancing wedge-shaped area and enhancing cortical rim.

  • Total absence of renal enhancement and no excretion and no perinephric hematoma (renal artery thrombosis).

  • Total absence of enhancement and large perinephric hematoma (renal artery avulsion).

  • "Cortical rim" sign: Reliable sign of subacute infarction.

  • Small-sized kidney with smooth or irregular contour (chronic infarction).
  • Pyelonephritis and acute infarction may have similar appearance.

  • Straight line demarcation and "cortical rim" sign favor infarction.

  • Perinephric stranding favors pyelonephritis.

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