A 50-year-old man is brought to the emergency department due to chest pain. He passed out briefly after the pain started. Medical history includes hypertension, hyperlipidemia, and early-stage chronic kidney disease. The patient reports that his father had a heart attack at a young age. Despite treatment, the patient dies during hospitalization. An autopsy is performed. Light microscopy of the aortic wall is shown on the slide below. Which of the following underlying mechanisms is most likely responsible for this patient's disease process?

Question

A 50-year-old man is brought to the emergency department due to chest pain.  He passed out briefly after the pain started.  Medical history includes hypertension, hyperlipidemia, and early-stage chronic kidney disease.  The patient reports that his father had a heart attack at a young age.  Despite treatment, the patient dies during hospitalization.  An autopsy is performed.  Light microscopy of the aortic wall is shown on the slide below.  Which of the following underlying mechanisms is most likely responsible for this patient's disease process?

Quizplus · Accepted Answer

The slide shows cystic degeneration of the media, which is a hallmark of cystic medial degeneration, also known as medial degeneration or elastic fiber fragmentation. This condition weakens the aortic wall and predisposes to aortic aneurysm and dissection. It commonly occurs in patients with hypertension, hyperlipidemia, and connective tissue disorders. Atherosclerosis, calciphylaxis, granulomatous inflammation, and Monckeberg sclerosis are not associated with this histological finding. 11ec160b_38b8_3392_9249_03da5ab28c32_MD0001_00 The above autopsy image shows cystic medial degeneration (necrosis), the classic histologic finding in aortic dissection.xa0 The tunica media is the largest and strongest of the 3 portions of the aortic wall.xa0 With aging, collagen, elastin, and smooth muscle in the aortic media are broken down and replaced by a mucoid extracellular matrix.xa0 There is elastic tissue fragmentation in a "basket weave" pattern with development of many cystic collections of mucopolysaccharide.xa0 These changes result in progressive loss of integrity, reducing the vessel's ability to handle wall stress from conditions such as systemic hypertension. Once cystic medial degeneration develops, a small intimal tear can readily extend into and throughout the media, creating a lengthy dissection plane that propagates proximally or distally.xa0 As blood enters the dissection plane a false aortic lumen is created and aortic branches (eg, left subclavian artery, renal arteries) may become obstructed.xa0 The enlarging hematoma in the false lumen can eventually penetrate the adventitia, resulting in full-thickness rupture. (Choice A)xa0 Atherosclerosis primarily affects the intima and is an important contributor to acute coronary syndrome.xa0 Histologically it appears as an atheroma with an endothelial covering, fibrous cap, and necrotic core.xa0 Atherosclerosis can contribute to cystic medial degeneration but is not the primary pathophysiologic mechanism. (Choice B)xa0 Calcific uremic arteriolopathy (calciphylaxis) can occur with advanced chronic kidney disease and leads to severe skin ischemia and necrosis.xa0 Histologically, it is characterized by superficial arteriolar calcification, subintimal fibrosis, and thrombosis.xa0 It does not typically affect large vessels such as the aorta. (Choice D)xa0 Granulomatous inflammation of large vessels can occur in Takayasu arteritis and tuberculous aortitis.xa0 Histopathology demonstrates granuloma formation in the media with multinucleated giant cells. (Choice E)xa0 Monckeberg sclerosis is a rare disease that results in diffuse medial calcification of small and medium-sized arteries.xa0 Calcification typically appears as blue-to-violet irregular deposits on hematoxylin-eosin stains, as seen in this calcified atherosclerotic plaque. Educational objective: Cystic medial degeneration (necrosis) is the classic histologic finding in aortic dissection, as it weakens the aortic wall and allows a small intimal tear to readily propagate.xa0 Collagen, elastin, and smooth muscle are replaced by a basophilic mucoid extracellular matrix with elastic tissue fragmentation and cystic collections of mucopolysaccharide. __________ References: Impact of connective tissue disease on the surgical outcomes of aortic dissection in patients with cystic medial necrosis. (http://www.ncbi.nlm.nih.gov/pubmed/29169363) Cystic medial necrosis: pathological findings and clinical implications. (http://www.ncbi.nlm.nih.gov/pubmed/21881719)

A 50-Year-Old Man Is Brought to the Emergency Department Due