A 60-year-old hypertensive man has a dissecting aortic aneurysm. Microscopy of the aortic media shows loss of elastic and smooth muscle fibers with pools of basophilic ground substance material, no inflammatory cells. This is:

• A Atherosclerotic plaque with foam cell infiltration
• B Fibrinoid necrosis due to malignant hypertension
• C Granulomatous aortitis due to giant cell arteritis
• D Cystic medial degeneration (cystic medionecrosis) — pooling of proteoglycans in areas of smooth muscle and elastic fiber dropout ✓

Explanation

Cystic medial degeneration (Erdheim cystic medionecrosis) is characterized histologically by focal loss of smooth muscle cells and elastic fibers in the media with accumulation of basophilic proteoglycan-rich ground substance forming pools or 'cysts.' There is no inflammatory infiltrate. This weakens the aortic wall predisposing to dissection. It occurs in Marfan syndrome (FBN1 mutation), Loeys-Dietz syndrome, ehlers-Danlos type IV, and as an acquired change in hypertension and aging. Atherosclerosis involves intimal foam cells. Fibrinoid necrosis has eosinophilic amorphous material.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.