A 73-year-old man comes to the emergency department with unstable angina. He undergoes coronary angiography via the femoral approach. A stent is placed in the right coronary artery, and the patient is discharged. He returns to the emergency department 2 days later with blue discoloration of his right toe. He has pain and mild tingling in the affected toe. Medical history is significant for hyperlipidemia and coronary artery disease. On physical examination, the right toe appears cyanotic, and there is livedo reticularis affecting the right thigh. Peripheral pulses in the lower extremities are bilaterally palpable. Serum creatinine is 2.8 mg/dL (preoperatively it was 1.0 mg/dL). Which of the following histopathologic findings would most likely be seen on biopsy of this patient's kidney?

Question

A 73-year-old man comes to the emergency department with unstable angina.  He undergoes coronary angiography via the femoral approach.  A stent is placed in the right coronary artery, and the patient is discharged.  He returns to the emergency department 2 days later with blue discoloration of his right toe.  He has pain and mild tingling in the affected toe.  Medical history is significant for hyperlipidemia and coronary artery disease.  On physical examination, the right toe appears cyanotic, and there is livedo reticularis affecting the right thigh.  Peripheral pulses in the lower extremities are bilaterally palpable.  Serum creatinine is 2.8 mg/dL (preoperatively it was 1.0 mg/dL).  Which of the following histopathologic findings would most likely be seen on biopsy of this patient's kidney?

Quizplus · Accepted Answer

11ec160b_3a2a_fe1e_9249_7329d56a7f75_MD0001_00 This patient has livedo reticularis, a blue toe, and acute kidney injury following coronary angiography; this presentation is concerning for atheroembolic disease. Invasive vascular procedures (eg, angiography, angioplasty, aortic surgery) can cause cholesterol-containing debris from atherosclerotic plaques to become dislodged from large arteries (eg, the aorta during cardiac catheterization) and shower microemboli into the circulation. These lodge in small, distal arterioles, resulting in ischemia of the corresponding organs and tissues; symptoms develop within a few days or weeks after the procedure. Skin findings (eg, livedo reticularis, blue toe syndrome) are the most common presenting signs. Pulses typically remain palpable as larger arteries are unaffected. Signs of acute kidney injury (eg, oliguria, azotemia) are common in the setting of postprocedure atheroembolism and are frequently seen in elderly patients with preexisting renal atherosclerosis. Frank infarction with flank pain and hematuria does not occur due to the small size of the emboli. Cholesterol is dissolved during tissue preparation for microscopic evaluation, leaving the needle-shaped clefts that partially or completely obstruct the arcuate or interlobular renal arteries. Other organs that may be involved are the gastrointestinal tract and the CNS, including the retinal vessels. (Choice B) Glomerular crescent formation is characteristic of rapidly progressive glomerulonephritis (RPGN). All forms of RPGN have an insidious onset with hematuria, hypertension, and edema. (Choice C) Hyperplastic arteriolar changes (intimal fibroelastosis) are diagnostic of hypertensive nephropathy seen in patients with poorly controlled hypertension. (Choice D) Atheroemboli only partially occlude the renal vessels, therefore acute tubular necrosis (ATN) does not typically occur early in the disease process. Complete vessel occlusion with resultant ATN can occur later (weeks to months) due to an endothelial inflammatory response. However, as opposed to toxin-induced ATN (eg, aminoglycosides), which causes diffuse, extensive proximal tubular injury, ischemic ATN typically causes patchy necrosis of the proximal tubules. (Choice E) Urate nephropathy due to tubular obstruction from urate crystal deposition is usually seen in individuals with acute hyperuricemia (eg, tumor lysis syndrome). The classic presentation is acute renal failure during chemotherapy for a malignancy. Educational objective: Invasive vascular procedures can be complicated by atheroembolic disease, which may involve the kidneys, gastrointestinal tract, CNS, and the skin. Light microscopy shows a partially or completely obstructed arterial lumen with needle-shaped cholesterol clefts within the atheromatous embolus. __________ References: Atheroembolic kidney disease. (http://www.ncbi.nlm.nih.gov/pubmed/29494024)

A 73-Year-Old Man Comes to the Emergency Department with Unstable