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 has become smaller as secondary sequelae from various other pathologies. In an adult patient the distinction 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