WBR0292

Author	[[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Renal
Prompt	[[Prompt::A 68-year-old man presents to his physician for his annual check-up. The patient’s past medical history is significant for hypertension well-controlled on lisinopril and advanced type II diabetes mellitus poorly controlled on daily insulin injections. Routine work-up reveals elevated serum creatinine. A renal biopsy under light microscopy similar to the patient’s biopsy is shown in the image below. The following findings could be best explained by which of the following pathologic processes? ]]
Answer A	AnswerA::Amorphous pink deposits of amyloid in renal cortex
Answer A Explanation	[[AnswerAExp::Amyloidosis is characterized by amyloid deposition that is positive for Congo red stain.]]
Answer B	AnswerB::Immune response mediated by CD4 and CD8 lymphocytes
Answer B Explanation	[[AnswerBExp::Immune response mediated by CD4 and CD8 lymphocytes describes the mechanism of renal rejection following transplantation.]]
Answer C	AnswerC::Cystic distribution throughout the renal parenchyma
Answer C Explanation	[[AnswerCExp::Polycystic kidney disease is characterized by cystic distribution throughout the renal parenchyma.]]
Answer D	AnswerD::Immune complex deposition activating the complement pathway
Answer D Explanation	[[AnswerDExp::The pathogenesis of several primary glomerulonephritides, including post-infectious glomerulonephritis and membranoproliferative glomerulonephritis, is characterized by immune complex deposition that activates the complement pathway.]]
Answer E	AnswerE::Non-enzymatic glycosylation of proteins
Answer E Explanation	AnswerEExp::Diabetic nephropathy is a common microvascular complication in advanced diabetes mellitus. Renal biopsy under light microscopy would reveal characteristic eosinophilic nodules in the glomerular tuft called “Kimmelsteil-Wilson” lesion.
Right Answer	RightAnswer::E
Explanation	[[Explanation::Diabetic nephropathy is a common microvascular complication of advanced diabetes mellitus. Renal biopsy under light microscopy typically demonstrates characteristic eosinophilic nodules in the glomerular tuft called “Kimmelsteil-Wilson” lesions. Chronic hyperglycemia results in accumulation of advanced glycosylation end-products (AGEs) that trap extravasated immunoglobulins, albumin, LDL, and other proteins via cross-linking to the extravascular matrix. Educational Objective: Diabetic nephropathy is a microvascular complication of uncontrolled diabetes mellitus. It is characterized by Kimmelsteil-Wilson lesions, which are eosinophilic nodules in glomerular tufts. The pathogenesis of diabetic nephropathy is thought to be due to accumulation of advanced glycosylation end-products (AGEs). References: Kalia K, Sharma S, Mistry K. Non-enzymatic glycosylation of immunoglobulins in diabetic nephropathy. Clin Chim Acta. 2004;347(1-2):169-76. First Aid 2014 page 327, 537]]
Approved	Approved::Yes
Keyword	WBRKeyword::Diabetic nephropathy, WBRKeyword::Diabetes mellitus, WBRKeyword::Kimmelsteil-Wilson lesion, WBRKeyword::Microvascular complication, WBRKeyword::Renal failure, WBRKeyword::Glomerulonephritis
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::