["Milk-of-calcium" renal cyst (author's transl)]

In milk-of-calcium renal cysts a suspension of fine calcific sediment is contained in a pyelogenic cyst. This very rare condition may be misinterpreted as solid renal calculi. The true roentgenologic diagnosis is established by films taken with the patient upright or sitting: the calcific material gravitating to the bottom of the cyst results in the characteristic half-moon contour.