This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urinary tract, Subject name: Pathology
Necrotizing papillitis is a feature in all of the following conditions except - 
Select and explain. 
A. Sickle cell disease, B. Tuberculous pyelonephritis, C. Diabetes mellitus, D. Analgesic nephropathy
B: Tuberculous pyelonephritis
Answer: B: Tuberculous pyelonephritis 
Explanation: Necrotizing papillitis (or papillary necrosis): It is one special pattern of acute pyelonephritis and is much more frequent in diabetics compared to nondiabetics. Hyaline aeriolosclerosis narrows blood vessels -> reduces the blood supply to the renal medulla -> ischemia ->causes necrosis of the tips of papillae (papillary necrosis). Causes of necrotizing papillitis: Diabetes mellitus Sickle cell anemia Analgesic nephropathy Obstructive uropathy. Ref: RAM DAS NAYAK EXAM PREPARATORY MANUAL FOR UNDERGRADUATES 2nd ed. pg no: 615