What is a pseudoaneurysm?

A pseudoaneurysm is characterized as a condition where there is a rupture in the arterial wall, resulting in blood leakage that is enclosed by surrounding tissues or fibrous tissue. This encapsulation around the blood forms a false aneurysm, which is why it is termed "pseudo" as it does not involve all three layers of the arterial wall as in a true aneurysm. The encapsulated area can increase in size over time, and, depending on its location and cause, may lead to complications but is distinct from other vascular conditions.

The other options describe different vascular problems that do not accurately define a pseudoaneurysm. An abnormal widening of a blood vessel refers to an aneurysm; a blockage leading to tissue necrosis pertains to ischemic conditions; and a permanent injury to the artery could describe various vascular injuries but does not neatly fit the definition of a pseudoaneurysm. Thus, option B is the most accurate and fitting description of a pseudoaneurysm.