대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Lung lobar torsion of the right middle lobe

Radiologic Findings

Fig 1. Chest PA shows right pleural effusion shifting the mediastinum to the left. The left lung looks relatively normal.
Fig 2-3. Axial CT scans with mediastinum window reveal poorly enhancing consolidation and increased volume of the right middle lobe. The right middle lobe is unusually located medial to the right upper lobe. Some pulmonary arteries are noted but venous structures are not evident.
Fig 4. Axial CT scan with lung window reveals well-defined margin of consolidation.
Fig 5. Coronal CT scan shows superiorly dislocated right middle lobe.
Fig 6. Sagittal MIP image shows bronchial obstruction of the right middle lobe.
Fig 7. One month ago, chest PA also showed large amount of right pleural effusion but the right middle lobe was small in volume due to passive atelectasis.

Brief Review

Lung torsion is a rare but potentially life-threatening event whereby a lobe or the entire lung twists about its pedicle, leading to venous congestion and/or hemorrhagic infarction. The most common clinical scenario is right middle lobe torsion after right upper lobectomy, which accounts for approximately three quarters of cases.
Other underlying circumstances that favor the development of pulmonary torsion include: (a) An airless lobe, consolidated or atelectatic, (b) A long, free, lobar pedicle, (c) Absence of a parenchymal bridge between contiguous lobes, (d) Pneumothorax or pleural effusion, (e)Transection of the inferior pulmonary ligament.
The degree of rotation in pulmonary torsion is generally 180°, although on occasion, 90°or 360° torsion has been recorded. Torsion of hilar structures and especially of the pulmonary veins leads to impaired circulation with reflux into the venous pathways, resulting in interstitial edema and alveolar exudation.
CT findings include tapered obliteration of the proximal pulmonary artery and accompanying bronchus of the involved lobe. The torsed lobe demonstrates poorly enhancing consolidation with increased volume, ground-glass attenuation, interlobular septal thickening, and intralobular linear attenuation.
In this case, VATS operation demonstrated 90° torsion of the right middle lobe and occlusion of the pulmonary vein.

Please refer to

Case 93, Case 171, Case 317, Case 943, Case 991, Case 1066,

References

1. Mark M. Hammer, Rachna Madan. Clinical and imaging features in lung torsion and description of a norvel imaging sign. Emerg Radiol. 2018; 25: 121-127.
2. Benjamin Felson. Lung torsion: Radiographic findings in nine cases. Radiology. 1987; 162:631-638.
3. Eun A. Kim, Kyung Soo Lee, Young Mog Shim, Jhingook Kim, Kwanmien Kim, Tae Sung Kim, Po Song Yang. Radiographic and CT findings in complications following pulmonary resection. Radiographics, 2002; 22:67-86.

Keywords

lung, right middle lobe, lung torsion,