Pulmonary artery pseudoaneurysm

Pulmonary artery pseudoaneurysm refers to a pseudoaneurysm arising from the pulmonary arteries.

Pathology

A pseudoaneurysm results from a tear or disruption of all three layers of a vessel wall. Extravasated blood is contained by compressed extravascular tissue or a clot, which makes up the wall of the pseudoaneurysm. Histologically, a pseudoaneurysm involves only the external layers of the arterial wall (the media and adventitia).

They can arise from a number of causes including

infection
- can occur from various infective etiology including mycotic, syphilis, mycobacterial infection
associated neoplasms
trauma - post traumatic pulmonary arterial pseudoaneurysm (ususally rare)
- extravascular trauma
  - mostly occur from penetrating trauma such as gunshot injuries or stab wounds
  - pseudoaneurysms due to blunt trauma have been rarely reported .
- intravascular trauma: iatrogenic insults: rare cases due to Swan-Ganz catheter placement have been rarely reported.
pulmonary valvular and post-valvular stenosis and increased flow due to left-to-right shunting.

Associations

conditions that predispose to vascular wall anomalies such as
pulmonary hypertension

Location

In general they tends to have a strong predilection for the peripheral pulmonary arteries with most located in segmental and subsegmental pulmonary arteries .

Radiographic features

CT chest / CT pulmonary angiography

CT pulmonary angiography is considered the gold standard and may show focal dilatation of a segment of the involved pulmonary arterial segment (may be contained or not contained depending on status at time of scan).

Treatment and prognosis

Prognosis is not well described (probably due to rarity) and may depends on multiple variables such as associated injuries / pathology, age, hemorrhagic diathesis, size and delay before diagnosis. Treatment options may include surgical lung resection, embolotherapy / coil embolization).