This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidney, Subject name: Pathology
Irregular scarred kidney with pelvic dilatation is seen with - 
Select and explain. 
A. Chronic pyelonephritis, B. Polycystic kidney, C. Renal artery stenosis, D. Tuberculosis of kidney
A: Chronic pyelonephritis
Answer: A: Chronic pyelonephritis 
Explanation: Ans. is 'a' i.e., Chronic pyelonephritis Pathological changes of chronic pyelonephritis area) Irregular scarring of kidneyb) The hallmarks of chronic pyelonephritis are coarse corticomedullary scars overlying blunted calyces; dilated pelvis and flattening of papillae.c) The microscopic changes involve predominantly tubules and interstitium; and include :-o Atrophy of tubules in some areas and hypertrophy or dilatation in other areas.o Thyroidization of tubules :- Dilated tubules with flattened epithelium filled with colloid casts resemble colloid containing thyroid follicles.o Chronic interstitial inflammation with interstitial fibrosisd) Arcuate and interlobular vessels demonstrate obliterative intimal sclerosis in the scarred areas; and in the presence of hypertension, hyaline arteriosclerosis is seen in the entire kidney.