A 65-year-old man is found to have an aortic aneurysm. Histology shows cystic medial necrosis with loss of elastic fibers and smooth muscle cells in the tunica media. This pattern is most characteristic of which aortic aneurysm etiology?

• A Atherosclerotic abdominal aortic aneurysm
• B Syphilitic (luetic) aortitis causing ascending aortic aneurysm
• C Inflammatory aortic aneurysm due to periaortic fibrosis
• D Marfan syndrome or hereditary aortopathy causing ascending thoracic aortic aneurysm ✓

Explanation

Cystic medial necrosis (CMN) — pooling of basophilic mucoid material within the media, with loss of smooth muscle cells and elastic fibers — is the histological hallmark of hereditary aortopathies such as Marfan syndrome (FBN1 mutation) and Loeys-Dietz syndrome. CMN predisposes to thoracic aortic aneurysm and aortic dissection. Atherosclerotic AAA shows intimal atherosclerotic plaques and medial thinning/inflammation. Syphilitic aortitis shows endarteritis obliterans of vasa vasorum with plasma cell infiltration. Inflammatory aneurysms show periaortic adventitial fibrosis with lymphocyte/plasma cell infiltration.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.