A 50-year-old hypeensive man develops very severe, "tearing" chest pain, which migrates from his upper back to mid-back over the period of an hour. Pathologic examination of a specimen removed from the patient during emergency surgery would MOST likely demonstrate which of the following?

This is a classic description of a dissecting aoic aneurysm, a very impoant condition that may cause death if missed or misdiagnosed. Dissecting aneurysms are actually dissecting hematomas, with the blood located between the middle and outer thirds of the media of the aoa. Dissecting aneurysms are associated with hypeension in many cases; they are also associated with cystic medial degeneration of the wall of the aoa (seen in Marfan's syndrome). Often, an intimal tear is present; these are thought to represent the staing point for the dissection. Unlike abdominal aoic aneurysm and syphilitic aneurysm, aoic dissection is not usually associated with aoic dilatation.The pain of myocardial infarction does not usually move.Plasma cells around the vasa vasorum and "tree-barking" (wrinkling of the aoic intima; ) are features of syphilitic aneurysms. Ref: Rapp J.H., MacTagga J. (2010). Chapter 34. Aeries. In G.M. Dohey (Ed),CURRENT Diagnosis & Treatment: Surgery, 13e.