CTICasesSarcoidosis with Aortopulmonary Interface Sign and Right-Sided Companion Shadow Loss
Imaging findings
Chest radiograph in a patient with bilateral hilar and right paratracheal lymphadenopathy from sarcoidosis demonstrates displacement of the aortopulmonary pleural reflection interface leftward compared to normal, indicating left paraaortic lymphadenopathy pushing the lung laterally. The lateral view shows effacement of the posterior wall of the bronchus intermedius (intermediate stem line) from subcarinal lymphadenopathy. The bilateral companion shadows of the clavicles are diminished or absent, suggesting bilateral supraclavicular lymphadenopathy. Follow-up radiograph one month later shows the aortopulmonary interface moving back toward normal as nodes shrink.
Key takeaways
The aortopulmonary pleural reflection (also called aortopulmonary window interface) on chest radiograph is the interface between left upper lobe lung and the aorto-pulmonary window region. Medial displacement of this interface indicates left paraaortic or subcarinal lymphadenopathy pushing the lung laterally, a more sensitive sign than obvious aortic knuckle fullness. On the lateral view, loss of the intermediate stem line (posterior wall of bronchus intermedius) indicates hilar or subcarinal lymphadenopathy preventing lung contact with that structure. Loss of companion shadows above the clavicles on the PA view suggests supraclavicular adenopathy.
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