- Permanent dilatation of the main and/or segmental pulmonary arterial branches which can be congenital or acquired.
- Congenital – rare condition seen in adolescent females with dilatation of the main pulmonary artery. Patients are usually asymptomatic with only a soft ejection systolicmurmur detectable.No significant complications. The diagnosis is made after excluding other acquired conditions.
- Infections (e.g. TB, known as Rasmussen aneurysm, where there is mycotic inflammatory necrosis causing dilatation of the arterial wall).
- Collagen vascular disorders (e.g. Marfan’s syndrome).
- Inflammatory (e.g. Takayasu’s arteritis).
- Behc¸et’s disease. Segmental artery dilatation is a feature of Hughes–Stovin syndrome.
- Post trauma – blunt (RTA), or direct (following arterial instrumentation).
- Post stenotic dilatation in pulmonary valvular stenosis.
- Thromboembolic disease.
- Associated with primary bronchial neoplasm.
- Clinical presentation depends on the underlying cause and location of the aneurysm.
- Congenital lesions are uncommon and asymptomatic.
- Acquired lesion – most commonly present with haemoptysis. Rupture may complicate the clinical picture and is frequently fatal.
- In many cases diagnosis is incidental following investigations for the underlying primary disease.
- CXR – isolated main pulmonary artery dilatation in the aortopulmonary window with normal lungs is a rare radiological finding. More commonly the aneurysm lies within an ill-defined area of consolidation and is difficult to fully appreciate.
- Contrast-enhanced CT scanning allows clearer appreciation of the size, location and extent of the arterial aneurysm(s).
- CT also allows for further assessment of the underlying cause. An increasing focal lung mass raises the possibility of aneurysm. Lack of an arterial wall and a history of trauma support the diagnosis of a false aneurysm of the pulmonary artery.
- Themain differential lieswithin the varying underlying causes listed above.
- Management is dependent on identifying the abnormalities, correlating with the clinical history, and excluding the various different conditions.
- Sputum culture, echocardiography, cardiac catheterisation and arterial wall biopsy may all play a role in the diagnostic pathway.
- Treatment options are targeted first at the correct management of the cause.
- Surgical repair of the aneurysm and the use of endovascular stent grafts are rarely used strategies, but potentially offer definitive treatment.