Renal milk of calcium cysts

Last revised by Dr Ammar Haouimi on 28 Dec 2020

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

Renal milk of calcium cysts are typically asymptomatic. 

  • 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 
  • 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

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

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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Cases and figures

  • Case 1: erect radiograph
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  • Case 1: ultrasound
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  • Case 2
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  • Case 3
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