Abstract
We report a large hydrocalyx with multiple calculi resembling renal cyst with milk of calcium. A 15-year-old female presented with intermittent colicky right flank pain for 10 years with recent increase in pain severity and frequency. Renal ultrasound and CT abdomen revealed right upper pole renal cyst. To further evaluate, retrograde pyelogram was done which delineated a hydrocalyx with narrow infundibulum filling and draining slowly causing renal colic. Thulium Fiber Laser (TFL) was used to perform laser infundibulotomy and stone fragmentation. TFL has lower depth of penetration and hence was useful for ureteroscopic endoincision in this case.