The bronchial sign is an imaging term, also known as the air bronchial sign, which is an important sign of lung solidity, indicating that the proximal part of the airway is patent and the air in the alveoli has been absorbed or replaced by inflammation.
The bronchial sign is an imaging manifestation found by imaging tests, including X-ray, CT, and MRI. When a lung solid lesion extends around the hilum, the larger air-containing bronchioles contrast with their surrounding solid lung tissue, and the air-containing bronchiolar shadows are seen in the area of the solid lesion, i.e., the bronchial sign. The bronchial sign is commonly seen in the solid phase of lobar pneumonia.
The presence of a bronchial sign indicates that the proximal airways are patent and that the air in the alveoli has been absorbed or replaced by inflammation, or has disappeared as a result of a combination of both; loss of alveolar air as a result of significant interstitial distension is also, but less commonly, observed.
The detection of bronchial signs requires prompt medical attention and standardized treatment under the guidance of a medical professional.