<prompt> Which of the following is the most common renal cystic disease in infants is ?Polycystic kidneySimple renal cystUnilateral renal dysplasiaCalyceal cyst  <response>: Unilateral renal dysplasia is a form of renal dysplasia RD; see this term, a renal tract malformation in which the development of one kidney is abnormal and incomplete. Unilateral RD can be segmental, and of variable severity, with renal aplasia corresponding to extreme RD. Reference: GHAI Essential pediatrics, 8th edition 