Medullary Sponge Kidney (MSK) is a rare disorder of the kidney that is caused by small pockets forming on the kidney tubules and is often associated with excess calcium in the urine and also alterations in other constituents of the urine. It may cause recurrent stone disease. Stone disease can associated with pain in the flank area.
There are web sites that offer information about MSK including our web site at:
There is also the NIH web site at: https://www.niddk.nih.gov/health-information/kidney-disease/children/medullary-sponge-kidney