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I got it right, but I want clear explanation for better understanding. Thank you

A 55-year-old woman comes to the emergency department 30 minutes after the sudden onset of ripping substernal chest pain. She has hypertension treated with hydrochlorothiazide. Her blood pressure is 220/128 mm Hg in both arms. Carotid, radial, femoral, and pedal pulses are within normal limits. An x-ray of the chest shows a widened aortic root and dilated ascending aorta. Which of the following is the most likely cause?

A) Aortic dissection due to Takayasu arteritis
B) Degeneration of the aortic wall from Marfan syndrome
C) Medial degeneration of the aorta
D) Rupture of a sinus of Valsalva aneurysm
E) Traumatic disruption of the aorta from a fall

i would go with C. and offer my thought process, hoping it help
the vignette describes the clinical scenario of acute aortic dissection (acute onset ripping chest pain,widened aortic root and dilated ascending aorta on chest X-ray) in a 55 yo hypertensive female patients. So i would use the differential and pick the most likely cause among the plausible given. Chronic hypertension induced pathological degeneration of the aortic tissue (medial necrosis) and is the more plausible causes of aortic dissection .
A rupture of the Sinuses would be fatal (plus, it is not compatible with the chest x ray findings of dilated root and ascending aorta); we have no mention of a fall, so I would exclude C and D
Takayasu arteritis is a rare cause of dissection - more often causing arterial narrowing and thrombosis, although dissection is possible - , even though the demographic (female, 50ish) would be pertinent, and I would have wanted something more in the question to hint at that - associated signs and simptoms, asymmetric pulses. Same can be said for Marfan - no associated pertinent findings, that I would expect in a 55yo . if these patients dissect, they do so at a younger age...

C..

so there are two types of dissection..type A..proximal to left subclavian or type B..distal to subclavian..in this case.you have ascending disection of the aorta. this is treated medically ie surgery vs. type B..treated with just drugs..ie bp medication

now..AAA is due to atherosclerosis and huge RF of smoking..true anursym since it involves all layers.
ascending is due to cystic medial necrosis..not a true aneursym..just the inside of the artery is involved since its taking the blunt of the pressure from the LV..it can be caused by htn, syphillis (thoracic type more common), marfan, ehlors danlos.

since pt doesn't have marfans..you are left with option C

Great explanations.. Thank you elen_ithil & jazpreet2000!

answer is thanks Medial degeneration of the aorta...jazpeet2000 that was a good explanation