The presence of a nephroblastoma, which is a neoplasm of the kidney that primarily affects children.

Segmental accumulation of scar tissue in individual (but not all) glomeruli.

Nephrotic syndrome is a collection of findings resulting from glomerular dysfunction with an increase in glomerular capillary wall permeability associated with pronounced proteinuria. Nephrotic syndrome refers to the constellation of clinical findings that result from severe renal loss of protein, with Proteinuria and hypoalbuminemia, edema, and hyperlipidemia.

Thickening and scarring (sclerosis) of the mesangium (a structure in the glomerulus). The sclerosis affects a large portion of the mesangium across multiple glomeruli. Histologic features include an increase in the mesangial matrix, thickened glomerular basement membrane, tubular casts, and interstitial inflammation. Diffuse mesangial sclerosis presents with nephrotic syndrome at birth or within the first year of life. Glomeruli are small and condensed in appearance, with early lesions showing increased loose mesangial collagen that progress to sclerosis with dense collagen without hypercellularity. Podocytes do not show hyperplasia but may be immature and cobblestone-like. Electron microscopy shows extensive foot process effacement without deposits, but increased collagen within mesangial areas.

A reduction in the level of performance of the kidneys in areas of function comprising the concentration of urine, removal of wastes, the maintenance of electrolyte balance, homeostasis of blood pressure, and calcium metabolism.