Unilateral Hyperlucent Lung



Unilateral Hyperlucent Lung


Daniel J. Podberesky, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Endobronchial Obstruction/Foreign Body


  • Asthma


  • Pneumothorax


Less Common



  • Swyer-James Syndrome


  • Extrinsic Airway Compression by Mass Lesion


  • Vascular Ring/Sling


  • Scimitar Syndrome


  • Bulla


Rare but Important



  • Pulmonary Agenesis/Aplasia


  • Poland Syndrome


  • Pulmonary Embolus


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Appearance can result from variety of sources



    • Technical factors (rotation)


    • Chest wall abnormalities


    • Lung parenchymal abnormalities


    • Airway issues


    • Vascular abnormalities


  • Appearance of unilateral hyperlucent lung may be result of compensatory hyperinflation due to contralateral lung abnormality


  • Decubitus views can be helpful


  • Chest CT may be necessary in confusing cases


Helpful Clues for Common Diagnoses



  • Endobronchial Obstruction/Foreign Body



    • Food is most common aspirated foreign body



      • Peanuts most common food aspirated


    • Frequency of right vs. left bronchial tree involvement equal in young children


    • In adults, right > left


    • Air-trapping occurs distal to obstruction more commonly than atelectasis in children


    • Lateral decubitus radiographs helpful



      • Persistent air-trapping in obstructed lung


    • Fluoroscopy or expiratory images can also be utilized


  • Asthma



    • Most common chronic childhood disease


    • Airway inflammation results in intermittent airflow obstruction


    • Chest radiograph typically obtained to rule out other etiologies or complications



      • May be normal


      • May show bilateral hyperinflated, hyperlucent lungs


    • When lungs are asymmetrically involved, unilateral hyperlucent lung appearance may result



      • Must consider aspirated foreign body in these situations


  • Pneumothorax



    • Wide spectrum of etiologies in pediatric population


    • Can mimic appearance of unilateral hyperlucent lung


    • Radiolucent space lacking pulmonary markings


    • White pleural line visible


Helpful Clues for Less Common Diagnoses



  • Swyer-James Syndrome



    • Postinfectious obliterative bronchiolitis



      • Viral


      • Bacterial


      • Mycoplasma


    • Arrest of progressive normal lung growth secondary to vascular compromise


    • Small hyperlucent lung


    • Attenuated pulmonary vascularity


    • Air-trapping during expiration on high-resolution chest CT


  • Extrinsic Airway Compression by Mass Lesion



    • Any mass lesion in mediastinum or hila may compress tracheobronchial tree



      • Lymphadenopathy


      • Foregut duplication cysts


      • Neoplasm


    • Causative mass may not be apparent on plain radiograph


    • Chest CT may be necessary



      • 3D reformations can be helpful in identifying area of narrowing of tracheobronchial tree


  • Vascular Ring/Sling



    • Common forms that cause tracheobronchial compression



      • Double aortic arch



      • Right aortic arch with aberrant left subclavian


      • Pulmonary artery sling


    • Results in air-trapping and hyperlucency


    • CT or MR angiography diagnostic


  • Scimitar Syndrome



    • a.k.a. hypogenetic lung syndrome, pulmonary venolobar syndrome


    • Involved lung is hypoplastic


    • Systemic arterial supply


    • Venous return, typically to IVC



      • Resembles scimitar (Turkish sword)


    • Compensatory hyperinflation of contralateral lung



      • Appears hyperlucent


  • Bulla

Tags:
Aug 10, 2016 | Posted by in PEDIATRICS | Comments Off on Unilateral Hyperlucent Lung

Full access? Get Clinical Tree
Get Clinical Tree app for offline access