Final Diagnosis

Radiation-Induced Arteriopathy with Diffuse Iliofemoral Aneurysmal Disease

Reasoning - Point by Point

• Left external iliac artery
• Left common femoral artery
• Proximal superficial femoral artery
• Proximal profunda femoris artery
• Focal popliteal aneurysm (left popliteal, just above the tibial plateau)

• Pulsatile left groin mass (2.5 cm left femoral artery diameter - enlarged vs. normal) - consistent with a femoral aneurysm
• Severe left leg edema (+++pitting) - from venous/lymphatic compression by the aneurysmal mass, plus possible venous occlusion
• Absent dorsalis pedis pulse on the left + crescentic calcifications adjacent to the arterial lumen on CT - consistent with mural thrombus formation within the aneurysm, with distal thromboembolism causing left foot ischemia

• Lymphadenopathy / recurrent prostate or colon cancer: CT and physical exam showed NO enlarged retroperitoneal lymph nodes, the prostatic bed was flat, PSA and acid phosphatase were normal. Metastatic disease is excluded.
• Mycotic (infected) aneurysm: The patient was afebrile (37°C), WBC was normal, blood cultures are not mentioned as positive, there is no history of IV drug use or bacteremia. Mycotic aneurysm is much less likely.
• Primary atherosclerotic aneurysm: While the patient has cardiovascular risk factors (smoking, hypertension), purely atherosclerotic aneurysm would not typically produce this degree of diffuse, multi-segment involvement in the iliac-femoral distribution in a 68-year-old; the radiation history is the far more compelling etiology.
• Lymphedema alone: A pulsatile mass and absent foot pulses cannot be explained by lymphedema alone; an arterial etiology is required.

Summary Table

Final Diagnosis Statement

Radiation-induced diffuse aneurysmal arteriopathy of the left iliofemoral system (external iliac, common femoral, superficial femoral, profunda femoris, and popliteal arteries), with mural thrombus formation and distal thromboembolism causing left lower extremity ischemia - occurring as a late complication of pelvic irradiation for prostate carcinoma.

Recent Literature: Radiation-Induced Arterial Aneurysm Management

1. Pathophysiology - Why Radiation Causes Aneurysms

2. Endovascular Treatment - Peripheral Artery Pseudoaneurysms

• 12 patients with radiation-induced peripheral arterial pseudoaneurysms (mean size 20.4 mm, range 10-30 mm)
• Iliac artery most commonly involved, followed by subclavian artery
• All treated with covered stent deployment (7-8 mm diameter, 50 mm length); coil embolization added in 3 cases
• Primary technical success: 91.7%; secondary success: 100%
• One death from rebleeding; all others had no rebleeding on follow-up
• Conclusion: Endovascular stenting with covered stents is feasible and effective for radiation-induced peripheral pseudoaneurysms in selected patients

This is the best current evidence supporting endovascular-first management for the type of iliofemoral aneurysm seen in the case you analyzed.

3. Intracranial Radiation-Induced Aneurysms

• Mean latency: 11.3 years from radiotherapy to aneurysm diagnosis (range 2-21 years)
• Mean RT age: 36.7 years; mean aneurysm diagnosis age: 47.8 years
• Most common location: internal carotid artery (32%), posterior circulation (23%)
• 45.1% were dissecting or non-saccular (not typical berry aneurysms)
• Half presented with subarachnoid hemorrhage
• Endovascular treatment (coiling, stent-assisted coiling) used in ~2/3 of treated cases
• Occlusion rate: 73.1% for endovascular vs. 48.5% for surgical repair
• Conclusion: Endovascular approaches achieve superior occlusion rates compared to open surgery for radiation-induced intracranial aneurysms

4. Carotid Blowout Syndrome - The Most Studied Radiation-Induced Arterial Emergency

• 28 studies, 554 patients
• Compares reconstructive (stent/balloon, preserving flow) vs. deconstructive (vessel occlusion) endovascular strategies
• 30-day mortality: 10% - no significant difference between approaches
• Reconstructive (stent) group: higher rebleeding beyond 24 h and severe technical complications
• Complication rates decreased over time; long-term mortality increased for both
• Take-away: Endovascular is the primary modality; stents carry higher rebleed risk; deconstructive occlusion may be safer in poor surgical candidates

• 39 articles, 917 patients
• RT-to-CBS latency: 1.2 to 17.8 years
• Modalities compared: embolization, stent, bypass surgery, ligation, flap coverage
• Survival: 30-day 85.2%, 1-year 48.9%, 2-year 37.0%
• Lowest rebleed rate: bypass surgery (1.4%) vs. stent (35.6% - highest)
• Lowest neurologic complications: bypass (10.8%) vs. ligation (32.0% - highest)
• Conclusion: Embolization/stenting are mainstream but bypass surgery offers best outcomes for selected fit patients; endovascular is preferred in poor surgical candidates due to radiation-damaged tissue planes

• Supports early identification of at-risk patients and pre-emptive intervention before acute hemorrhage

5. Key Principles Synthesized from the Literature

Evidence Gap