WBR0075

Author	PageAuthor::Anonymous (Reviewed by Will Gibson and Yazan Daaboul)
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Cardiology
Prompt	[[Prompt::During a routine checkup, a 33-year-old woman is noted to have an elevated blood pressure of 180/120 mmHg and mild headache. She denies the presence of chest pain, shortness of breath, or frothy urine. Her thyroid-stimulating hormone, cortisol, and 24-hour urinary excretion of catecholamines are all within normal range. However, there is a string-of-beads appearance on an angiogram of her left renal artery. Which of the following pathologic findings is most likely to be observed from the lesional biopsy?]]
Answer A	AnswerA::Amorphous, proteinaceous material in the extracellular matrix
Answer A Explanation	[[AnswerAExp::The pink material resembling fibrin seen in the wall of this arteriole is indicative of the process of fibrinoid necrosis as a consequence of malignant hypertension. Hyaline arteriolosclerosis is a major morphologic characteristic of benign nephrosclerosis; in which the arteriolar narrowing causes impairment of renal blood supply and glomerular filtration rate, leading to increased renin secretion and decreased renal function.]]
Answer B	AnswerB::Homogeneous dysplasia of elastic tissue at the media
Answer B Explanation	[[AnswerBExp::Medial fibroplasia is the most common form of fibromuscular dysplasia. It is characterized by its classic “string of beads” appearance. Histologically, there is involvement of the media, with preservation of the intima, internal elastic lamina, and adventitia.]]
Answer C	AnswerC::Nuclear debris from infiltrating neutrophils in and around the vessels
Answer C Explanation	[[AnswerCExp::Cutaneous allergic (leukocytoclastic) vasculitis (CAV) is a small-vessel necrotizing vasculitis localized to the skin. It is associated with infection (such as HCV virus) and drugs. It manifests as polymorphic palpable purpura of the lower extremities that usually self-resolve within 1 month. Histologically, it is characterized by the presence of vascular and perivascular infiltration of neutrophils with leukocytoclasis, endothelial cell swelling, fibrin deposition, and RBC extravasation.]]
Answer D	AnswerD::Smooth muscle proliferation with lipid-laden foam cells
Answer D Explanation	[[AnswerDExp::Atherosclerotic plaques are rich in extracellular matrix and smooth muscle cells. Foam cells are macrophages that contain scavenger proteins that allow them to engulf oxidized low-density lipoproteins (LDL) via endocytosis. Consequently, they form fatty streaks of atheroma in the tunica intima of arteries.]]
Answer E	AnswerE::Thickened smooth muscle layer and duplicated basement membrane
Answer E Explanation	[[AnswerEExp::Hyperplastic arteriolosclerosis is a type of arteriolosclerosis involving a narrowed lumen. Onion-skin appearance is used to describe the thickened concentric smooth muscle cell layer and duplicated basement membrane. These changes are most prominent in the kidney and can lead to ischemia and acute renal failure. It can be caused by malignant hypertension. The pathogenesis of hypertension is associated with medial thickening that corresponds to narrowing or the luminal diameter of the blood vessels. Malignant hypertension is histologically characterized by its "onion-skin" appearance that is used to describe the thickened concentric smooth muscle cell layer and duplicated basement membrane.]]
Right Answer	RightAnswer::B
Explanation	[[Explanation::"String-of-beads" appearance of a renal artery is a classic finding suggestive of fibromuscular dysplasia. Fibromuscular dysplasia is a non-atherosclerotic, non-inflammatory vascular disease that has virtually been described in all arteries, but usually involves the renal and internal carotid arteries. Renovascular fibromuscular dysplasia usually affects women between 15 and 50 years of age. The disease is mostly associated with history of smoking and personal history of hypertension. Genetics may also play a role in the development of the disease. In most cases, the diagnosis is made incidentally, but symptomatic patients may present with signs and symptoms of hypertension. Patients are initially treated pharmacologically using antihypertensive therapy. Otherwise, the preferred treatment for specific and refractory cases is percutaneous balloon angioplasty. If the arterial wall is damaged or weakened, then stenting of the affected artery may be chosen. Histologically, the media of the blood vessels is involved in medial fibroplasia, the most common type of fibromuscular dysplasia. In such cases, the remaining layers, such as the intima, internal elastic lamina, and adventitia are preserved. However, some cases of perimedial fibroplasia involve the junction of the media and the adventitia with normal elastic components of media and intima. Less commonly, intimal and adventitial fibroplasia are also described. Educational Objective: Fibromuscular dysplasia affects the elastic tissue of the media of vessels. Clinically, it is characterized by a "string of beads" appearance of the renal artery. It is a cause of secondary hypertension, especially in middle-aged women. References: Slovut DP, Olin JW. Fibromuscular dysplasia. N Engl J Med. 2004;350:1862-71 Shi Y, Honma M, Koizumi F. Cutaneous allergic vasculitis: Clinicopathological characterization and identification of apoptosis. Pathol Int 1998;48(9):705-716. Alexander RW, Hennigar RA, Griendling KK. Pathogenesis of hypertension: Vascular mechanisms. in Atlas of Heart Diseases Eds. Hollenberg NK. 2001. Springer. First Aid 2014 page 284]]
Approved	Approved::Yes
Keyword	WBRKeyword::Artery, WBRKeyword::Vasculature, WBRKeyword::Fibromuscular dysplasia, WBRKeyword::Hypertension, WBRKeyword::Pathology, WBRKeyword::fibroplasia, WBRKeyword::string, WBRKeyword::beads
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