A peripheral aneurysm is a bulge that forms in a blood vessel outside the heart and brain, often occurring in the legs or arms. This condition happens when the vessel wall weakens, leading to an abnormal enlargement. Peripheral aneurysms can be caused by factors such as atherosclerosis, trauma, or infection. Symptoms may include pain, swelling, or a pulsating mass near the affected area. If left untreated, a peripheral aneurysm can lead to serious complications, such as blood clots or rupture. Diagnosis typically involves imaging tests like ultrasound or CT scans, and treatment options may include monitoring or surgical intervention.