Renal milk of calcium cysts

Dr Henry Knipe et al.

Renal milk of calcium cysts refer to the appearance of a calcium precipitate found 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. 

Renal milk of calcium cysts are more common in the upper renal pole.

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 artefact
  • posterior shadowing is present when large volumes of milk of calcium are present

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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Article Information

rID: 31508
System: Urogenital
Section: Pathology
Synonyms or Alternate Spellings:
  • Milk of calcium in renal cyst
  • Renal milk of calcium (MOC) cyst

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Cases and Figures

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    Case 1: erect radiograph
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    Case 1: ultrasound
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    Case 2
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