{'fraction_non_alphanumeric': 0.02633632461958642, 'fraction_numerical': 0.010144362075692548, 'mean_word_length': 4.968568102444703, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Right lung torsion diagnosed 6 months after a thoracoscopic right upper lobectomy

Abstract This report presents the case of a woman successfully treated with thoracoscopic detorsion of the right lung after she was diagnosed with a 180-degree torsion, 6 months after a video-assisted thoracoscopic right upper lobectomy for a stage 1 adenocarcinoma.


INTRODUCTION
Lung torsion is a rare complication after video-assisted thoracoscopic surgery (VATS). It is defined as a rotation of the lung or the lobar parenchyma around its bronchovascular pedicle, causing ischaemia and necrosis of the affected lung segment. The incidence is estimated to be 0.089% to 0.4% with a mortality of 8.3% [1]. The diagnosis is established with contrast-enhanced computed tomography (CT) and bronchoscopy, with findings such as misplacement and obstruction of the bronchovascular structures.
We present a case of 180-degree torsion of the right lung diagnosed 6 months after a VATS right upper lobectomy, successfully treated with VATS detorsion of the right lung.

DESCRIPTION
A 69-year-old female was diagnosed with a T1bN0M0 adenocarcinoma in the right upper lobe and a ground glass infiltration in the right middle lobe (RML). She experienced no respiratory symptoms and had a forced expiratory volume in 1 s of 71% of the expected volume. A 3-port anterior VATS right upper lobectomy and a wedge resection of the RML were performed. Perioperative findings revealed normal anatomy with welldefined fissures. The inferior pulmonary ligament was divided, and the RML and right upper lobe were correctly positioned, without being fixed. There were no postoperative complications, and the patient was discharged 3 days after the operation.
A routine follow-up examination was undertaken 3 months postoperatively, with a CT scan that was considered normal. The patient experienced moderate dyspnoea, but we failed to establish an explanation. At the 6-month follow-up, another CT scan showed no signs of recurrence. However, the patient underwent a diagnostic bronchoscopy due to increasing respiratory discomfort and the onset of expiratory stridor. This test revealed a partial occlusion of the distal part of the right lower lobe bronchus ( Fig. 1A-C). When the CT scan was reassessed, the RML could be seen to be rotated caudally, and the right lower lobe (RLL) was rotated cranially ( Fig. 2A). The patient was diagnosed with right lung torsion. A new VATS procedure was performed, which revealed massive adherences and the lung rotated 180 degrees, thereby positioning the RML in direct contact with the diaphragm. The lung was vital, and decortication and detorsion were performed without fixation. A postoperative CT scan showed normal placement of the right lung without any bronchial obstruction (Fig. 2B). The patient was discharged on postoperative day 10. Spirometry 5 months after surgery showed increased respiratory function with a forced expiratory volume in 1 s of 56% compared to 46% before redo surgery, and the patient was without symptoms.

DISCUSSION
The cause of this rare complication is elusive. The patient displayed normal lung anatomy and the initial surgery was uncomplicated. Previous reports in the literature have argued in favour of the perseverance of the inferior pulmonary ligament in an upper lobectomy as an approach to potentially prevent postoperative torsion [2]. In this case, the inferior pulmonary ligament was divided. Furthermore, the nature of the procedure, i.e. with both an upper lobectomy and a RML wedge resection, might increase the risk of torsion, but the evidence for this is sparse. In the majority of cases with lung torsion, the patient is symptomatic, with an abrupt onset of symptoms such as shortness of breath, fever and chest pain, shortly after the operation [3]. These symptoms are also reported in a systematic review from Dai et al. [1], where the median time from surgery to diagnosis was estimated to be 4 days. In this case, however, the patient presented with mild symptoms and was diagnosed with torsion 6 months postoperatively. This situation has, to our knowledge, never previously been reported. Reassessing the CT scan performed 3 months after the operation showed the same findings as the CT scan made 6 months after surgery; therefore, we concluded that the patient could have been diagnosed much earlier. It raises the suspicion that this complication may be underdiagnosed.
In summary, our findings suggest that, although it is a rare condition, lung torsion may be suspected in patients presenting with prolonged stridor and dyspnoea after anatomical lung resection.

Ethical statement
The patient provided written consent to publish this case report.
According to the Danish National Committee on Health Research Ethics: "Prevention, diagnostic procedures and therapy etc. involving a specific individual need not be notified." Conflict of interest: Henrik Jessen Hansen receives speakers' fees from Medtronic, Medela and BD. Ren e Horsleben Petersen receives speakers' fees from Medtronic and AMBU and is an advisory board member for AstraZeneca, Roche and MSD.