American Board of Pathology (ABPath) 2025 – 400 Free Practice Questions to Pass the Exam

A dissecting aneurysm is characterized by a tear in the arterial wall, which allows blood to flow between the layers of the artery. This type of aneurysm typically occurs in the aorta and is notable for its potential to cause severe complications, including rupture. The initial tear may originate from a pre-existing weakness in the artery wall, often exacerbated by conditions such as hypertension or connective tissue disorders.

In a dissecting aneurysm, a separation of the layers of the vessel wall occurs, creating a false lumen that can extend along the length of the artery. This process can lead to significant cardiovascular events depending on the location and extent of the dissection.

Other types of aneurysms, such as mycotic, saccular, and fusiform, do not involve tearing through the arterial wall in the same manner. Mycotic aneurysms are usually caused by an infection, causing the wall to weaken rather than tear. Saccular aneurysms are outpouchings that form on one side of the artery, and fusiform aneurysms involve a uniform dilation of the arterial wall without a discrete tear. Thus, the defining feature of a dissecting aneurysm is its association with a tear in the wall of the artery,