milk of calcium in renal cysts

Renal milk of calcium cysts refer to the appearance of a calcium precipitate found either within a calyceal diverticulum, that has lost communication with the collecting system, or within a simple renal cyst.

Clinical presentation

Renal milk of calcium cysts are typically asymptomatic.

Radiographic features

Plain radiograph
  • on erect or decubitus films, renal milk of calcium cysts have a characteristic crescentic opacity with a sharp upper border
  • will change shape to a more oval-shaped opacity on supine projections 
Ultrasound
  • dependent echogenic material within a hypoechoic cyst that demonstrates reverberation artifact
  • posterior shadowing is present when large volumes of milk of calcium are present
  • more common in the upper pole of the kidneys

Treatment and prognosis

Considered an incidental benign finding that does not require further treatment unless symptomatic.

Differential diagnosis

On supine plain radiographs, a renal milk of calcium cyst may be mistaken for a renal calculus. Milk of calcium can also occur within the gallbladder.

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