Pseudoaneurysmis a term that is used synonymously with false aneurysm, pulsatile hematoma, and communicating hematoma.1It is defined by the loss of integrity of 1 or more layers of the arterial wall, resulting in an aneurysmal sac that communicates with the lumen of the ruptured vessel and is encapsulated by adventitia and periarterial fibrous tissue. It differs from a true aneurysm, which has an intact but dilated vascular wall. The center cavity of a pseudoaneurysm creates a potential space for blood flow and development of thrombi and emboli, which accounts for the heterogeneous appearance on MRIs. Arterial pressures can stretch and enlarge this aneurysmal sac, eventually causing rupture, compression of the parent-artery lumen, or damage to adjacent structures.2As in the present case, these lesions can also spontaneously thrombose and regress on their own.
Radiology Quiz Case 2: Diagnosis. Arch Otolaryngol Head Neck Surg. 2008;134(5):557-558. doi:10.1001/archotol.134.5.557