Right Robotic-Assisted Azygous Lobectomy (Segmentectomy)

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In this video, the authors present a right robotic-assisted azygous lobectomy. An azygos lobe is found in less than one percent of the population (1).  
An azygous lobe forms when the azygous vein invaginates into the right upper lobe during early development. Despite being called a lobe, it is not a true accessory lobe, as it does not have its own bronchus or corresponding bronchopulmonary segment (2). In this video, the authors illustrate an azygous lobe, which challenges the current understanding. 
 
This was the case of a 74-year-old woman who presented with a progressively growing PET active 25 mm lesion limited to her azygous lobe, radiologically staged as T1c N0 M0. Not amenable to compute tomographic-guided biopsy, a decision was made to proceed with surgery. 
 
A four-port robotic approach was adopted in an incomplete W fashionusing 2 x 8 mm and 2 x 12 mm ports to dock the da Vinci Xi robotic surgical system.  
Upon entering the chest, the azygous lobe was visible medial to the azygous vein and a layer of parietal pleura. The lobe was then delivered from under the azygous vein to be inspected. 
 
As with a right upper lobectomy, the procedure started by exposing the superior hilum and commencing with the dissection of the superior hilar pleural reflection. The lung was positioned posteriorly to expose the anterior hilum. The anterior pleural reflections were dissected to expose the superior pulmonary venous branches.  
 
The azygous pulmonary vein branch was identified and dissected. Dissection continued on both sides of the vein. The team switched from the hook to a Cadier forceps to continue vein dissection posteriorly to create space for the stapler. A vascular curved-tip robotic stapler was then introduced to control the vein.  
 
Next, the dissection progressed to identify the azygous pulmonary artery. As with the vein, the tissue planes were developed on either side of the artery.  
Once again, the surgeons switched to a Cadier forceps to develop the posterior plane. At this point, only the azygous bronchus remained, and the surgeons proceeded by retracting the lung inferiorly to start the bronchial dissection. The bronchial dissection continued in the accessory azygous fissure. The bronchus was dissected on both sides to create space for the stapler. A blue stapler was introduced to divide the azygous bronchus.  
The fissure was then completed using multiple firings of thick staples green staples, taking care to include all vascular and bronchial stumps within the specimen. The specimen was then free and retrieved in a specimen bag to be sent for histological analysis. Local anesthetic was infiltrated as a multilevel intercostal nerve block to achieve postoperative pain control. A French 28 drain was inserted via the camera port, and the lung was inflated under direct vision. 

Postoperatively, the patient recovered well. The drain was removed on day one, and she was subsequently discharged home on the same day.  
Histology revealed a 32 mm mucinous adenocarcinoma staged pT2a N0 R0. Molecular testing detected an epidermal growth factor receptor (EGFR) mutation. She went on to receive adjuvant immunotherapy with Osimertinib. Two years later, she remained disease free. 
 
As witnessed, this woman had clear bronchopulmonary segmentation, which raises a few questions. 

First, should this procedure be considered a lobectomy or segmentectomy? 

Secondly, is there a need to apply the oncological principles that guide a segmentectomy? 

Finally, is this surgical technique reproducible for all azygous lobes, or is it only applicable for select cases where there is clear evidence of bronchopulmonary segmentation?

References

1. Akhtar J, Lal A, Martin K, Popkin J. Azygos Lobe: A Rare Cause of Right Paratracheal Opacity. Respir Med Case Rep. 2018;23:136-7. doi:10.1016/j.rmcr.2018.02.001 - Pubmed
2. Mata J, Cáceres J, Alegret X, Coscojuela P, De Marcos J. Imaging of the Azygos Lobe: Normal Anatomy and Variations. AJR Am J Roentgenol. 1991;156(5):931-7. doi:10.2214/ajr.156.5.2017954 - Pubmed

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