Atrophic Pyelonephritis Versus Congenital Renal Hypoplasia

There has been much discussion in the urological and pathological literature regarding the unilateral, abnormally small kidney. Many confusing terms have arisen to describe it, such as atrophic kidney, contracted kidney, atrophic pyelonephritis, congenital hypoplasia, infantile kidney, aplastic kidney, and agenesia. Some statements in the literature tend to leave one with the impression that these various terms describe separate clinical and pathological entities that may be distinguished easily clinically, urographically, or by gross or microscopic examination. The two descriptive terms that have become most widely used are "chronic atrophic pyelonephritis" and "congenital hypoplasia." Contrary to general opinion, it has been our impression that it is usually difficult, if not impossible, to distinguish these two entities, if in reality two such separate entities actually exist. A cursory review of the literature will reveal the great confusion that exists on this subject. Most standard American textbooks on urology base their classification and