View source for WBR0075

{{WBRQuestion
|QuestionAuthor=Anonymous (Reviewed by Will Gibson)
|ExamType=USMLE Step 1
|MainCategory=Pathology
|SubCategory=Cardiology
|MainCategory=Pathology
|SubCategory=Cardiology
|MainCategory=Pathology
|SubCategory=Cardiology
|MainCategory=Pathology
|MainCategory=Pathology
|SubCategory=Cardiology
|MainCategory=Pathology
|SubCategory=Cardiology
|MainCategory=Pathology
|SubCategory=Cardiology
|MainCategory=Pathology
|SubCategory=Cardiology
|MainCategory=Pathology
|MainCategory=Pathology
|SubCategory=Cardiology
|Prompt=During a routine checkup, a 33-year-old female is noted to have an elevated blood pressure of 180/120 mm Hg, mild headache without chest pain, shortness of breath, or proteinuria. 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 seen from the lesional biopsy?
|Explanation=String-of-beads appearance of a renal artery is a classic finding suggestive of fibromuscular dysplasia. Fibromuscular dysplasia is a nonatherosclerotic, noninflammatory vascular disease that most commonly affects the renal and internal carotid arteries but has been described in almost every arterial bed in the body. Renovascular fibromuscular dysplasia tends to affect women between 15 and 50 years of age. In most cases, these persons have been asymptomatic for many years, and fibromuscular dysplasia is discovered incidentally. The preferred treatment for refractory cases is percutaneous balloon angioplasty. If the arterial wall is damaged or weakened, then stenting of the affected artery may be chosen.
|AnswerA=Amorphous, proteinaceous material in the extracellular matrix
|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.
|AnswerB=Homogeneous dysplasia of elastic tissue at the media
|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.
|AnswerC=Nuclear debris from infiltrating neutrophils in and around the vessels
|AnswerCExp=Leukocytoclastic vasculitis is an inflammation of small blood vessels characterized by palpable purpura. It is the most common vasculitis seen in clinical practice. Leukocytoclasis refers to the damage caused by nuclear debris from infiltrating neutrophils in and around the vessels.
|AnswerD=Smooth muscle proliferation with lipid-laden foam cells
|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.
|AnswerE=Thickened smooth muscle layer and duplicated basement membrane
|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.
|EducationalObjectives=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,
|References=First Aid 2014 page 284
|RightAnswer=B
|WBRKeyword=Artery, Vasculature, Fibromuscular dysplasia, Hypertension, Pathology,
|Approved=Yes
}}