Chest imagingCase Type
García Tuells I., Martínez Encarnación L., Rodríguez Mondéjar R., Rodríguez Rodríguez M., Pérez Hernández G., Trejo Falcón J.Patient
32 years, male
A 32-year-old man came to the emergency department with mild hemoptysis (<100mL/day) of 10 days duration, with no respiratory symptoms or fever. He was an active smoker (10 cigarettes a day). He did not have any pre-existing respiratory disease.
Chest X-ray showed a remarkable volume reduction of the right lung with consecutive mediastinal shift to the right side and absent right hilar shadow.
CT scan with contrast media was performed to evaluate the anatomy of the mediastinum and lungs. CT images revealed the absence of the right pulmonary artery, volume loss of right lung and ipsilateral mediastinal shift. Arterial supply of the right lung was produced by numerous systemic collateral arteries were identified dependent on hypertrophic bronchial arteries, originated in descending aorta, with orthotopic and ectopic origin, that run through the right mediastinum and hilum. The pleuro-pulmonary interface shows multiple wedge-shaped pleural abnormalities due to transpleural branches, which run through the costal pleura and fissures, extended into thin intrapulmonary septa. Ground-glass opacity in apical segment of right superior pulmonary lobe was identified, compatible with pulmonar haemorrhage, which was believed to be caused by rupture of some dilatated transpleural vessels. No other abnormalities were found in the CT scan.
Unilateral absence of the pulmonary artery (IUAPA) is the congenital absence of the left or right pulmonary artery. Absence of the pulmonary artery is a result of misdevelopment of the proximal portions of sixth arch of embryonal circulation. In 60% it is associated with congenital heart disease, that we must look for: tetralogy of Fallot, coarctation of the aorta, subvalvular aortic stenosis, transposition of the great arteries and Scimitar syndrome. In the present case, no congenital heart disease was found. Adult patients with IUAPA can be asymptomatic (30%). The clinical presentation can be dyspnea, chest pain, pleural effusion and recurrent bronchopneumonias  due to hypoperfusion and V-Q mismatch. Hemoptysis is caused by rupture of dilatated collateral vessels.
In chest X-ray we will find a volume reduction of one hemithorax with ipsilateral mediastinal and tracheal shift, ipsilateral hemidiaphragm elevation, absent hilar shadow, a reticular pattern in the hemithorax affected due to collateral circulation and contralateral lung hyperinflation with prominent pulmonary artery. In CT scan we will see the absence of pulmonary artery (more common right side), dilatated bronchial arteries and transpleural branches.  It also can show bronchiectasis secondary to recurrent bronchopneumonias.  Pulmonary hypertension is the most important factor of the prognosis.
Differential diagnosis of unilateral volume reduction in chest X-Ray includes Swyer-James Syndrome that, unlike UAP, manifests as unilateral hemithorax lucency, as a result of postinfectious obliterative bronchiolitis, with decreased vasculature. Also, we have to think of congenital abnormalities of the pulmonary artery (unilateral hypoplasia or aplasia) and volume loss due to chronic pneumonia or previous surgery.
The treatment depends upon the clinical presentation and the presence of pulmonary hypertension. Surgical modalities available to patients with hemoptysis or recurrent infections include pneumonectomy, embolization and closure of selected collateral arteries . In our patient hemoptysis was self-limited, and no specific treatment was needed.
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