WBR0292
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| Author | [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]] |
|---|---|
| Exam Type | USMLE Step 1 |
| Main Category | Pathology |
| Sub Category | 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?
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| Answer A | 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 | 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 | Cystic distribution throughout the renal parenchyma |
| Answer C Explanation | [[AnswerCExp::Polycystic kidney disease is characterized by cystic distribution throughout the renal parenchyma.]] |
| Answer D | 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 | Non-enzymatic glycosylation of proteins |
| Answer E Explanation | 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 | 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). |
| Approved | Yes |
| Keyword | Diabetic nephropathy, Diabetes mellitus, Kimmelsteil-Wilson lesion, Microvascular complication, Renal failure, Glomerulonephritis |
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