IS case 547: Congenital pulmonary airway malformation
Imaging Sciences URMC 2010
Publication Date: 2010-09-18
Patient is a 55-year-old female who presented to the emergency department with dyspnea on exertion, worse over the last 4 months and recent stress test that was concerning for right ventricular (RV) strain. A CT scan with pulmonary embolus protocol was ordered for question of pulmonary embolus. Two weeks prior the patient had presented with cough and underwent a chest radiograph, which revealed no acute infiltrate.
Congenital pulmonary airway malformation
This patient has a long history of various cardiopulmonary complaints, including the recent diagnosis of acute pulmonary embolus. Imaging findings include a ventilation defect, with partial perfusion reverse matching. Radiography is challenging, but corresponds to CT demonstration of a multicystic, segmental lesion, with a focal lung compression/consolidation at the inferior aspect. The differential diagnosis for this cystic lesion would include:
1. Congenital cystic adenomatoid malformation (CCAM), which has been more recently termed congenital pulmonary airway malformation (CPAM). CPAM is a disorganized hamartomatous malformation, that is typically unilateral, communicates with the bronchial tree, and has a normal arterial supply. * Type 0 is fatal in utero. * Type 1 is the most common (60 to 70%), with large cysts 2-10 cm, and can present later. * Type 2 cysts measure < 2 cm. * Type 3 appear solid, with a microcystic structure. * Type 4 cysts are large and peripheral.
2. Segmental bronchial atresia does not communicate with central airways, and appears nodular, cystic, hyperinflated, with typical location in an apicoposterior segment. 3. Pulmonary sequestration may be intralobar or extralobar. Sequestrations have do not have normal vascular or bronchial connections to the lung: intralobar types are typically fed from the thoracic aorta and drain to the pulmonary veins, with diagnosis in children and adults; extralobar types are often fed from the abdominal aorta and drain to systemic veins, with diagnosis in neonates. 4. Post-infectious pneumatocele(s). 5. Congenital lobar emphysema occurs with hyperinflation.
CPAM lesions may show ventilation defects on VQ imaging. This patient most likely has a Type 1 CPAM, given age of onset and imaging appearance. Histopathologic confirmation would be required to provide a definitive diagnosis.
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