The gross appearance of the kidney shown below is most compatible with which of the following conditions?

The kidney shown is typical of chronic pyelonephritis with dilation of the renal pelvis, clubbing of the calyces, and irregular reduction in parenchymal mass. Chronic pyelonephritis is an asymmetric, irregularly scarring process that may be unilateral or bilateral. Microscopically, there is atrophy and dilation of tubules with colloid in some tubules. Chronic inflammation and fibrosis occur in the coex and medulla. Chronic glomerulonephritis causes bilateral symmetrically shrunken and scarred kidneys. Histologic changes depend on the stage of the disease. Cystic dysplasia is characterized by undifferentiated mesenchyme and immature cailage and collecting ductules. Reference: Robbins & Cotran Pathologic Basis of Disease, 9edition