VASCULAR CAUSES OF ABSENT/SMALL HILUM – 64 SLICE CT

ABSTRACT ID : IRIA - 1198

30 yr old female came with

c/o chest pain,

shortness of breath,

recurrent respiratory tract infections,

anasarca,

CXR:Small right hemithorax with hyperlucency noted,Displacement of the mediastinum, to right sideAbsent hilar shadow and paucity of vascular markings on right lung field ,Prominence of left hilum with pulmonary plethoraCystic lucencies noted in b/l lower zonehyperinflation of the left lung.

CT CHEST PLAIN

Right lung shows volume loss with mediastinal shift to right sideCystic bronchiectatic changes noted on right side

CT PULMONARY ANGIOGRAM

Enlarged main pulmonarey artery (3.8cm) and left pulmonary artery(2.4cm),Absent right pulmonary arteryDecreased pulmonary vasculature noted on right sidePulmonary plethora on the left side.

Prominence of the left pulmonary artery branchesThe right pleural surface appears beaded because of the presence of prominent intercostal arteries serving as collateral vessels.

Reconstructed ,VR images Patent ductus arteriosusProminent main pulmonary artery,Left pulmonary artery

DIAGNOSIS

UNILATERAL ABSENCE OF PULMONARY ARTERY (Right pulmonary artery

agenesis)

Associated with

Pulmonary hypertension

Patent ductus arteriosus

UNILATERAL ABSENCE OF PULMONARY ARTERY

UAPA is estimated to be around 1 in 200,000 individuals The main embryologic defect is an involution of the proximal sixth aortic arch of the

affected side, leading to an absence of the proximal pulmonary artery. Intrapulmonary vessels and distal portion of the affected pulmonary artery trunk can

develop normally, and blood supply is achieved by systemic collaterals from bronchial, major aortopulmonary collaterals and other systemic arteries

UAPA is twice as common on the right side

Symptoms- Due to large systemic - pulmonary collaterals from

bronchial,intercostal,internalmammary arteries. Hemoptysis – 10% due to rupture of these hypertrophied collaterals. Recurrent chest infections Pulmonary hypertension - >40yrs.

Left-sided agenesis seems to be more frequently associated with cardiac abnormalities such as tetralogy of Fallot, septal defects, patent ductus arteriosus, coarctation of the aorta and transposition of great vessels and therefore early diagnosis and surgical repair are required during the first year of life.

Patients with isolated right UAPA survive into adulthood with minimal symptoms,

making the diagnosis of such cases more difficult.

UNILATERAL ABSENCE OF PULMONARY ARTERY

The radiologic features Small hemithorax, Ipsilateral displacement of the mediastinum, Absence of the corresponding pulmonary artery, Reticular densities along the pleura and within the lung, - due to systemic collateral

circulation. Ipsilateral hemidiaphragm elevation with volume loss of the affected lung, Absent hilar shadow, hyperinflation of the contralateral lung.

CAUSES OF UNILATERAL HYPERLUCENT HEMITHORAX

Patient positioning   Rotation   Scoliosis

Chest wall defect   Mastectomy   Poland syndrome (absent pectoralis muscle)

Pneumothorax C/L Pleural effusion Airway obstruction

   Bronchial compression (hilar mass, cardiomegaly)   Endobronchial obstruction with air trapping (foreign body, tumor)   Obliterative bronchiolitis   Swyer-James syndrome   Pulmonary emphysema (asymmetric)   Congenital lobar emphysema Pneumatocele

Pulmonary vascular cause   Pulmonary embolism   Pulmonary artery hypoplasia

CT – IN UAPA

lack of an identifiable pulmonary artery. enlarged intercostal arteries serving as collateral vessels to the lung marked volume loss in the lung. The pleural surface appears beaded because of the presence of prominent intercostal

arteries serving as collateral vessels. presence of smaller than usual branches of the inferior pulmonary vein compared with

the normal-sized other side inferior pulmonary vein. Pulmonary plethora on the other side. High resolution CT scanning can evaluate the presence of bronchiectasis in cases of

recurrent bronchopulmonary infections. Pulmonary hypertension

Angiography remains the gold standard for the diagnosis of pulmonary artery agenesis.

With the development of CT, MRI and magnetic resonance angiographic techniques –it is rarely performed unless embolization is indicated for massive hemoptysis.

DIFFERENTIAL DIAGNOSIS

Swyer-James-MacLead (SJM) syndrome should be considered in the differential diagnosis of pulmonary artery agenesis.

Perfusion scintigraphy or pulmonary angiography can be used for the differentiation. The pulmonary artery is hypoplastic in patients with SJM syndrome, air trapping in

expiration and ipsilateral lung perfusion is absent. On the other hand,pulmonary artery can not be observed in patients with UAPA, but

peripherally perfusion can be seen via collaterals.

COMPANION CASE

13 year old boy Cough Mild dyspnea h/o ?near drowning Pulmonary infection in early childhood

Increased lucency on left sideSmall hilum on left side compared to right

INSPIRATION

EXPIRATION – Increased lucency on left side due to Air trapping with mild mediastinal shift to right

CT ANGIOGRAM

Hyperlucenct lung(Left) Air trapping on expiration Left small hilum Diminished Left side pulmonary vascularity Normal lung volume h/o insult to bronchial tree Ruling out other conditions of diffuse air trapping

VOLUME RENDERED AND CORONAL RECONSTRUCTION - shows small left pulmonary artery.

SWYER JAMES/ MACLEOD SYNDROME

(UNILATERAL EMPHYSEMA,UNILATERAL LOBAR EMPHYSEMA,UNILATERAL HYPERLUCENT LUNG)

• Swyer-James syndrome (McLeod syndrome) • unilateral post infectious bronchiolitis obliterans in infancy and early childhood. • presence of concentric fibrosis involving the submucosal and peribronchial tissues of

terminal and respiratory bronchioles ,resulting in bronchial narrowing or obliteration

Radiological features… Nonspecific Large lung volume Small hilum Increased lung lucency(60%) Reduced size of peripheral vessels Central bronchiectasis HRCT – decreased lung attenuation -- decreased vessel caliber -- air trapping -- bronchiectasis / atelectasis

TAKE HOME MESSAGE…

Small hemithorax, Ipsilateral displacement of the mediastinum, Absence of the corresponding pulmonary artery, Reticular densities along the pleura and within the lung, - due to systemic collateral circulation,Absent hilar shadow, hyperinflation of the contralateral lung.

UNILATERAL ABSENCE OF PULMONARY ARTERY

Unilateral hyperlucency with evidence of air trapping,reduced size of pulmonary vessels,small hilum,bronchiectasis and history of some insult to the bronchial tree during early childhood

SWYER JAMES SYNDROME