Atypical findings in a patient with a renal milk-of-calcium cyst.

A case of an atypical renal milk-of-calcium cyst is presented. Although this cyst contained a colloidal suspension of calcium crystals, other signs and findings typical for a milk-of-calcium cyst were lacking. No connection of the cyst to the collecting system could be identified, no "half moon" phenomenon was found on upright and cross-sectional radiography, and the biopsies taken from the wall of the cyst showed sclerosis instead of urothelium. From the present case it was concluded that renal milk-of-calcium cysts may sometimes occur in the absence of findings that are typical of this particular entity. Therefore, this disease should be considered in the differential diagnosis of renal calcifications of unknown origin.