An 8-year-old girl with repeated right lower lobe pneumonias has a chest radiograph showing a reduced volume right hemithorax, a small right pulmonary artery, and a curvilinear tubular shadow running from the hilum toward the diaphragm just lateral to the right cardiac border. Contrast study confirms drainage of the entire right lung into the inferior vena cava. What is the most likely diagnosis?

• A Sinus venosus atrial septal defect with right upper pulmonary vein drainage into the superior vena cava
• B Scimitar syndrome, a form of partial anomalous pulmonary venous connection ✓
• C Cor triatriatum sinister
• D Total anomalous pulmonary venous connection of the infracardiac type

Explanation

Scimitar syndrome consists of anomalous drainage of part or all of the right lung into the inferior vena cava, together with right lung hypoplasia, a small right pulmonary artery, and recurrent ipsilateral infections. The curved scimitar-shaped vein hugging the right cardiac border is the diagnostic radiographic clue. Sinus venosus defects drain to the superior vena cava, infracardiac TAPVC presents as a obstructed cyanotic neonate, and cor triatriatum mimics mitral stenosis.

Reference: Nelson Textbook of Pediatrics, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.