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.
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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.