Renal milk of calcium cysts

Last revised by Tariq Walizai on 27 Jun 2024

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

Cases and figures

  • Case 1: erect radiograph
  • Case 1: ultrasound
  • Case 2
  • Case 3
  • Case 4: in a calyceal diverticulum
  • Case 5: in a calyceal diverticulum
  • Case 6: in a renal cyst
  • Case 7: in a renal cyst
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