Renal hypoplasia refers to a congenitally small kidney where there is essentially normal residual parenchyma but smaller calyces, lobules and papillae. This is in contrast to renal atrophy where renal development was initially normal but the kidney has become smaller secondary to various other pathologies. In an adult patient the distinction of the former from the latter however can be difficult.
Renal hypoplasia can be divided into two broad groups:
- complete (global) renal hypoplasia
- segmental renal hypoplasia: Ask-Upmark kidney