What is the differential diagnosis for a patient, particularly an adult over 60 years old with a history of hypertension, atherosclerosis, or previous aortic disease, presenting with symptoms suggestive of an aortic aneurysm?

Differential Diagnosis for Aortic Aneurysm

When evaluating a patient with suspected aortic aneurysm, the differential diagnosis must prioritize life-threatening acute aortic syndromes and other cardiovascular emergencies that present with similar symptoms, particularly in adults over 60 with hypertension and atherosclerosis. 1

Acute Aortic Syndromes (Highest Priority)

Aortic Dissection

• Most critical differential - presents with abrupt onset severe chest or back pain (84-90% of cases), maximal at onset, described as sharp, stabbing, tearing, or ripping 1, 2
• Type A dissection (ascending aorta) causes anterior chest pain in 71% of cases 2
• Type B dissection (descending aorta) causes interscapular back pain in 64% of cases 2
• Associated findings include pulse deficits, systolic blood pressure differential >20 mmHg between arms, new aortic regurgitation murmur, and focal neurologic deficits 1, 2
• Critical pitfall: 6.4-15% of dissections are painless, particularly in older patients, those on steroids, and Marfan syndrome patients 1, 2, 3

Intramural Hematoma (IMH)

• Represents 10-20% of acute aortic syndromes 1
• Type I: smooth inner aortic lumen, diameter <3.5 cm, wall thickness >0.5 cm 1
• Type II: occurs with aortic atherosclerosis, rough inner surface, aorta dilated >3.5 cm, calcium deposits frequently present 1
• Can progress to frank dissection over time 1
• Appears as low-attenuation band in aortic wall on CT 1

Penetrating Atherosclerotic Ulcer (PAU)

• Atherosclerotic lesion penetrating internal elastic lamina, allowing hematoma formation in media 1
• Occurs in >90% of cases in descending thoracic aorta 1
• Classic appearance: mushroom-like outpouching with overhanging edges 1
• Typical patient: elderly (>65 years), hypertensive, diffuse atherosclerosis 1
• Can lead to IMH, dissection, or frank rupture 1

Ruptured or Leaking Aneurysm

• Acute abdominal, back, or flank pain with known AAA should be presumed impending rupture 4
• Periaortic stranding or soft tissue changes on CT indicate rupture 4
• Pleural or peritoneal effusions suggest contained or complete rupture 4
• Fever present in ≥70% of ruptured AAA cases 4

Cardiovascular Differentials

Acute Coronary Syndrome (with or without ST-elevation)

• Key distinguishing feature: pain in ACS starts slowly and gains intensity over time, described as oppressive and dull, versus abrupt maximal onset in dissection 1
• 25% of aortic dissections may have ECG changes mimicking ACS 5
• Inferior wall MI should raise suspicion for dissection 5

Aortic Regurgitation without Dissection

• Can occur with aortic root or ascending aortic dilatation 1
• May present with heart failure symptoms 1
• Requires echocardiography to distinguish from dissection-related AR 1

Pericarditis

• Listed as differential in European Heart Journal guidelines 1
• Pain typically positional, pleuritic, relieved by sitting forward
• Friction rub may be present

Pulmonary Differentials

Pulmonary Embolism

• Included in guideline differential diagnosis 1
• Dyspnea more prominent than in aortic pathology
• D-dimer elevated in both conditions (>0.5 µg/mL has 91-100% sensitivity for dissection) 2

Pleurisy

• Sharp, pleuritic chest pain worsened by breathing 1
• Pleural effusion occurs in 16% of acute dissections at presentation 1

Other Important Differentials

Musculoskeletal Pain

• Pain reproducible with palpation or movement 1
• Gradual onset, not maximal at onset

Mediastinal Tumors

• Chronic progressive symptoms 1
• Compressive symptoms: hoarseness, stridor, dysphagia, superior vena cava syndrome 1

Cholecystitis

• Right upper quadrant pain, Murphy's sign 1
• Abdominal pain occurs in 21% of Type A and 43% of Type B dissections 2

Atherosclerotic or Cholesterol Embolism

• Distal embolization with end-organ symptoms 1
• Blue toe syndrome, livedo reticularis

Traumatic Aortic Rupture

• History of deceleration injury, motor vehicle accident, fall 1
• 20% of motor vehicle fatalities have ruptured aorta at autopsy 1
• Only 9-14% reach hospital alive 1

Aortic Pseudoaneurysm

• Related to trauma, prior surgery, catheter-based interventions, or infection 1
• Slim "neck" leading to aneurysm sac on imaging 1

High-Risk Conditions Requiring Immediate Consideration

Genetic/Congenital Disorders (particularly in younger patients):

• Marfan syndrome, Loeys-Dietz syndrome, vascular Ehlers-Danlos syndrome, Turner syndrome 1, 6
• Bicuspid aortic valve 1, 6
• Family history of aortic dissection or thoracic aortic aneurysm 1

Recent Aortic Manipulation:

• Surgical or catheter-based procedures 1
• Known thoracic aortic aneurysm 1

Critical Clinical Approach

When evaluating suspected aortic pathology, immediately assess:

• Blood pressure in both arms (differential >20 mmHg suggests dissection) 1, 2
• Peripheral pulses for deficits 1
• Auscultate for new diastolic murmur of aortic regurgitation 1
• Neurologic examination for focal deficits 1
• Pain characteristics: abrupt maximal onset favors dissection over ACS 1, 2

Imaging sequence:

• CT angiography of chest, abdomen, pelvis is diagnostic test of choice for dissection (100% sensitivity) 7
• Ultrasound for AAA screening (99% sensitive, 98% specific for AAA presence) 4
• Normal chest X-ray does NOT exclude dissection (mediastinal widening present in only 62.6% of Type A, 56% of Type B) 2