WBR250

Author	[[PageAuthor::Gerald Chi (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Vascular
Prompt	[[Prompt::A 33-year-old woman presents to her physician's office with complaints of headache and shortness of breath. She denies any chest pain, weakness of the extremities, cough, runny nose, or abdominal symptoms. In the clinic, her temperature is 36.7 °C (98.2 °F), her blood pressure is 182/122 mmHg, her heart rate is 20/min, and her respiratory rate is 22/min. Physical examination is remarkable for an abdominal bruit upon auscultation in the left periumbilical region. Work-up demonstrates normal values for thyroid-stimulating hormone (TSH), cortisol, and 24-hour urinary excretion of catecholamines. Abdominal angiogram demonstrates a string-of-bead appearance of the left renal artery. Which of the following pathologic findings is most likely to be found on lesional biopsy from her left renal artery?]]
Answer A	AnswerA::Amorphous, proteinaceous material in the extracellular matrix
Answer A Explanation	[[AnswerAExp::The pink material resembling fibrin in the wall of this arteriole is indicative 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 a reduction in 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, which is characterized by its classic “string of beads” appearance, represents the most common type of fibromuscular dysplasia. Histologically, there is involvement of the media, whereas the intima, internal elastic lamina, and adventitia are preserved.]]
Answer C	AnswerC::Nuclear debris from infiltrating neutrophils in and around the vessels
Answer C Explanation	[[AnswerCExp::Leukocytoclastic vasculitis is an inflammation of small blood vessels characterized by palpable purpura. It is the most common vasculitis in clinical practice. Leukocytoclasis refers to the damage caused by nuclear debris from infiltrating neutrophils in and around the vessels.]]
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 engulf oxidized low-density lipoproteins by endocytosis via scavenger receptors and form the 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 that may result from malignant hypertension. Thickened concentric smooth muscle cell layer and duplicated basement membrane on histopathological analysis is often termed onion-skin appearance. These changes are most prominent in the kidney and can lead to ischemia and acute kidney injury.]]
Right Answer	RightAnswer::B
Explanation	[[Explanation::Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory vascular disease that most commonly affects the renal and internal carotid arteries. Nonetheless, FMD has been described in virtually all arterial beds. On abdominal angiogram, FMD is characterized by a string-of-bead appearance that is suggestive of arterial beaing, typically in the middle-to-distal segment of the renal artery. On histopathological analysis of the vascular lesion, FMD demonstrates involvement of the media, with preservation of other vascular layers such as the intima, internal elastic lamina, and adventitia. Renovascular fibromuscular dysplasia tends to affect women between the age of 15 and 50 years. In the majority of cases, individuals with FMD remain asymptomatic for many years, and fibromuscular dysplasia is often discovered incidentally. Management of renovascular FMD includes pharmacologic therapy to control blood pressure, especially ACE-inhibitors. Percutaneous balloon angioplasty is usually reserved for patients who have uncontrollable blood pressure despite optimal pharmacologic therapy, patients who cannot tolerate pharmacologic therapy, or patients whose renal function is compromised. Educational Objective: Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory vascular disease that most commonly affects the renal and internal carotid arteries. Medial fibroplasia, which is characterized by its classic “string of beads” appearance, represents the most common type of fibromuscular dysplasia. On abdominal angiogram, FMD is characterized by a string-of-bead appearance that is suggestive of arterial beaing, typically in the middle-to-distal segment of the renal artery. Histologically, there is involvement of the media, whereas the intima, internal elastic lamina, and adventitia are preserved. References: Poloskey SL, Olin JW, Mace P, et al. Fibromuscular dysplasia. Circulation. 2012;125:e636-9. Slovut DP, Olin JW. Fibromuscular dysplasia. N Engl J Med. 2004; 350:1862-71. First Aid 2015 page 290.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Fibromuscular dysplasia, WBRKeyword::Hypertension, WBRKeyword::String of beads
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::