Aortic Aneurysms

A 68-year-old man with a 40-year history of smoking and poorly controlled hypertension (BP 160/95 mmHg) presents to the emergency department with sudden-onset severe tearing chest pain radiating to the back. On examination, he is diaphoretic and anxious. Blood pressure is 180/110 mmHg in the right arm and 140/85 mmHg in the left arm. Chest X-ray shows a widened mediastinum. CT angiography with contrast reveals a dissection flap extending from the ascending aorta to the descending thoracic aorta, with involvement of the left subclavian artery. Which of the following is the most appropriate immediate management?

A 72-year-old man with a 50-year smoking history, chronic obstructive pulmonary disease, and hypertension presents with a 3-month history of progressive lower back pain and abdominal pain. On examination, he is afebrile, and a pulsatile abdominal mass is palpable. Serum creatinine is 1.8 mg/dL (baseline 1.0). CT angiography shows a 6.5 cm infrarenal abdominal aortic aneurysm with eccentric thickening of the wall, periaortic fat stranding, and a crescent-shaped hematoma within the aneurysm wall. What is the most likely pathological diagnosis?

Which histopathological finding is most characteristic of abdominal aortic aneurysm (AAA) due to atherosclerotic degeneration?