A 65-year-old hypertensive man develops an acute aortic dissection. CT shows an intimal tear in the ascending aorta. The underlying histological change in the aortic media that predisposes to dissection is:
- A Lipid-laden macrophage (foam cell) accumulation in the medial layer
- B Cystic medial necrosis — mucoid extracellular matrix accumulation (myxomatous change) with fragmentation of elastic fibers and loss of smooth muscle cells ✓
- C Granulomatous inflammation with giant cells destroying elastic laminae (syphilitic aortitis)
- D Calcific deposits replacing smooth muscle cells in the media
Explanation
Cystic medial necrosis (Erdheim's medial necrosis, now termed medial degeneration) is the characteristic histological lesion predisposing to aortic dissection. It shows fragmentation and loss of elastic fibers, loss of smooth muscle cells, and accumulation of mucopolysaccharides (myxoid/mucoid change) creating cystic spaces in the aortic media. It occurs with aging and hypertension, and is accelerated in connective tissue disorders (Marfan, Ehlers-Danlos type IV). Syphilitic aortitis (obliterative endarteritis of vasa vasorum) causes aneurysm of the ascending aorta but via a different mechanism (adventitial inflammation).
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.