Rare complex anatomical variation of right pulmonary vessels and bronchi: a case report

Introduction

The patterns of bronchopulmonary vascular bifurcation within the lung exhibit considerable diversity. For general thoracic surgeons, it is extremely important to have a complete understanding of the anatomy of the pulmonary vessels and bronchi, including anatomical variations, to perform safe and accurate anatomical pulmonary resections (1). In the past, preoperative computed tomography (CT) imaging was the sole method available for assessing patients’ pulmonary anatomy, which often lacked intuitive clarity. However, the advent of 3-dimensional (3D) reconstruction technology has significantly enhanced preoperative planning. Numerous studies have demonstrated that 3D reconstruction technology provides a more precise representation of the anatomical structures and variations of pulmonary blood vessels and bronchi (2-6). In this article, we report on a rare case involving complex variations of the right pulmonary bronchi, arteries, and veins. The nomenclature used in this paper are based on the “Illustrated Anatomical Segmentectomy for Lung Cancer” atlas by Nomori and Okada (7). We present this article in accordance with the CARE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1073/rc).

Case presentation

A 66-year-old female patient was admitted to our department with a peripheral solid nodule approximately 1.5 cm in diameter in the right upper lobe (Figure 1A), which was detected by a chest CT scan. It was highly suspected to be early-stage lung cancer, and video-assisted right upper lobectomy was planned. During the preoperative CT imaging examination, we identified anatomical variations of the patient’s right pulmonary bronchi, arteries, and veins. We further performed a 3D CT reconstruction of the pulmonary vessels and bronchi using Mimics Medica 21.0 software (Materialise, Belgium) for this patient.

Figure 1 CT images of pulmonary nodule and bronchi variation. (A) (CT axial image) A nodule in the right upper lobe (red arrow). (B) (CT coronal image) B1+3 (yellow arrow) arose from the right main bronchus at the level of the carina. The displaced B2 (red arrow) arose separately from the right main bronchus (under B1+3). (C) (3D right lateral view) Separated B1+3 and B2. (D) (3D anterior view) Separated B1+3 and B2, absent B7. B1+3, apical and anterior segmental bronchi; B2, posterior segmental bronchus; RMB, right middle lobe bronchus; B7, inner basal segmental bronchus; CT, computed tomography; 3D, 3-dimensional.

From the 3D reconstruction, we were able to observe clearly that the apical and anterior segmental bronchi (B1+3) shared a common trunk, which arose from the lateral wall of the right main bronchus at the level of the carina. The posterior segmental bronchus (B2) was laterally displaced, arose separately from the right main bronchus (under B1+3), and subsequently divided into two branches: the posterior branch (B2a) and the lateral branch (B2b) (Figure 1B-1D). The right middle lobe bronchus (RMB) originated normally from the right intermediate pulmonary bronchus, but the inner basal segmental bronchus (B7) of the right lower lobe bronchus (RLB) was absent (Figure 1D).

Regarding the arterial abnormalities, in addition to the truncus anterior (TA), which contained the apical segmental artery (A1), the anterior segmental artery (A3), and the recurrent artery (Rec.A2) of the posterior segment (S2), at the intermediate pulmonary artery, there were 2 ascending A2 (Asc.A2), which we called double Asc.A2, that split off and distributed side by side to independently supply the lateral sub-segment of the independent S2 (Figure 2). Correspondingly, due to the absence of B7, the artery of the inner basal segment (A7) was also absent.

Figure 2 TA and double Asc.A2 (red arrows). (A) 3D anterior view. (B) 3D right lateral view. TA, truncus anterior; Rec.A2, recurrent artery; Asc.A2, ascending A2; 3D, 3-dimensional.

The variations in the veins of the right pulmonary were even more complex. The right superior vein (SPV) contained only the central vein (CV), which drained from all the apical and anterior segments (S1+3) as well as part of the independent S2. In addition, a variant vein originated from the uppermost of the right inferior pulmonary vein (IPV) and drained from the independent S2 through the posterior mediastinum (Figure 3). Furthermore, the right middle lobe vein drained into the IPV, rather than the SPV (Figure 3B-3D).

Figure 3 Veins variation and the 3D anatomical structure of the nodule and right lung vessels and bronchi. (A) (CT axial image) SPV (yellow arrow) contained only CV. (B) (CT axial image) Right middle lobe vein (yellow arrow) drained into the IPV, a variant vein (red arrow) originated from the uppermost of IPV drained from the independent S2 through the posterior mediastinum. (C) (3D anterior view) Branching patterns of the right pulmonary veins. (D) (3D right lateral view) Right middle lobe vein (yellow arrow) drained into the IPV. (E) (3D posterior view) The variant vein (red arrow) originated from the IPV drained from the independent S2. (F) (3D right lateral view) The 3D anatomical structure of the nodule and right lung vessels and bronchi. IPV, inferior pulmonary vein; SPV, superior vein; 3D, 3-dimensional; CT, computed tomography; CV, central vein.

The intraoperative pathology of the patient indicated invasive adenocarcinoma. We performed video-assisted right upper lobectomy and mediastinal lymph node dissection. Postoperative pathology suggested stage IA, and the surgical procedure was successful without misjudgment of the blood vessels. The patient recovered well and was discharged after 3 days.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki (as revised in 2013). Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

International Multidisciplinary Team (iMDT) discussion

Discussion among physicians from Lishui Municipal Central Hospital

An understanding of the anatomy of the pulmonary blood vessels and bronchi, including variations, is of utmost importance to general thoracic surgeons. Misjudging the anatomy may lead serious complications (8). Previously, we could only rely on preoperative CT images to understand the patients’ pulmonary anatomy, which was not always intuitive. However, currently, 3D reconstruction technology is widely used. Many studies have shown that 3D reconstruction technology can more accurately demonstrate the anatomical structure and variations of the pulmonary blood vessels and bronchi before surgery, guide surgeons to perform surgeries more safely, reduce intraoperative bleeding, save surgery time, and facilitate improved patient recovery (2-6). The study by Seguin-Givelet et al. showed that preoperative 3D modeling and tracking simplified the steps of thoracoscopic segmentectomy and should be considered as part of the surgery (9). Xie et al. used 3D technology to evaluate the practical classification patterns of the pulmonary arteries and bronchi in 358 patients. These data can be used by clinicians for teaching pulmonary artery anatomy and preoperative preparation for anatomical lobectomy (10).

However, 3D technology had some limitations, including the duration necessary for preoperative reconstruction and, in certain instances, the associated costs. Therefore, our center only performed 3D reconstruction in patients with abnormalities found in CT images or in patients who need complex lung segmentectomy.

We also utilized preoperative chest CT images to roughly understand the patient’s anatomical variations, and consequently applied 3D reconstruction to further visualize the intricate anatomical variations of the right pulmonary vessels and bronchi, ultimately accomplishing the surgery successfully.

We conducted a comprehensive review of prior studies that investigated bronchial and vascular variations in the right lung utilizing 3D reconstruction, bronchoscopy, or autopsy specimens (1,11-14). These articles described various bronchial and vascular variations. However, complex bronchial and vascular variations in a single patient like those described in this article have not been reported. Anatomical abnormalities of the S2 have been documented in several case reports (15-17). However, other complex variants similar to those found in the present case have not been reported in these cases. Nagashima et al. (1) conducted an analysis of variations in the right upper pulmonary bronchovascular structures in a cohort of 263 patients using three-dimensional reconstruction techniques. Their findings indicated that the incidence of the CV type (where V1–3 drain into the CV) was 7%, and the incidence of V2 associating with the lower pulmonary vein was 1.9%. However, the study did not describe the specific subtype of the CV+ variation in V2, nor did it report any bronchial or arterial variations similar to those observed in the present case. Nagashima et al. conducted another study involving 3D reconstructions derived from a cohort of 270 patients, through which they identified variations in the bronchovascular structures of the right middle and lower lobes (18). Their findings indicated that the incidence of complete merging of the middle lobar vein into the lower lobar vein was 4.1%, while the incidence of partial merging was 3%. Notably, the study did not report any instances of a missing B7 or A7.

Several issues on the diagnosis and treatment of this patient were further discussed as follows

Question 1: What should we do if we find a variant pulmonary vessel which is unclear before surgery?

Expert opinion: Dr. René H. Petersen

When the anatomy is unclear on CT, a 3D reconstruction should be performed. If a segmentectomy is planned a 3D reconstruction is recommended according to the European Society of Thoracic Surgeons (ESTS) Consensus document, published recently (19). During surgery it is recommended to do careful dissection of hilar structures before division.

Question 2: Misjudgment of the blood vessel and ligation, how should we remedy it?

Expert opinion: Dr. René H. Petersen

If a vein accidently is ligated, necrosis most likely will occur and the corresponding segment/lobe should be removed. If an artery is accidently ligated, the area will not be perfused, however no necrosis will usually occcur. If it is a small vessels, no further action is needed, however if a major vessel is transected, an anastomosis should be performed.

Question 3: In addition to 3D reconstruction, what other techniques do we have to help us better understand the anatomy of pulmonary bronchovascular anatomy?

Expert opinion: Dr. René H. Petersen

Intraoperative careful dissection before dividing any hilar structures may promote accidental transection. This was recommended in an analysis of major intraoperative complications during video-assisted thoracoscopic anatomical lung resections from the ESTS MITIG group (Minimally Invasive Thoracic Surgery Interest Group) (8).

Conclusions

To our knowledge, complex variations involving the right pulmonary bronchi, arteries, and veins such as this case have not been reported in previous literature. We hope this article can remind all thoracic surgeons to evaluate the variations of pulmonary blood vessels and bronchi thoroughly and comprehensively before surgery and formulate appropriate surgical plans to ensure the successful implementation of the surgery.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1073/rc

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1073/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1073/coif). R.H.P. serves as an unpaid editorial board member of Journal of Thoracic Disease from October 2022 to September 2024. R.H.P. receives speaker fee from Medtronic, AstraZeneca, AMBU, Medela and serves as the Advisory Board of AstraZeneca, BMS, Roche, MSD. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki (as revised in 2013). Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Nagashima T, Shimizu K, Ohtaki Y, et al. An analysis of variations in the bronchovascular pattern of the right upper lobe using three-dimensional CT angiography and bronchography. Gen Thorac Cardiovasc Surg 2015;63:354-60. [Crossref] [PubMed]
2. Liu Y, Zhang S, Liu C, et al. Three-dimensional reconstruction facilitates thoracoscopic anatomical partial lobectomy by an inexperienced surgeon: a single-institution retrospective review. J Thorac Dis 2021;13:5986-95. [Crossref] [PubMed]
3. Xue L, Fan H, Shi W, et al. Preoperative 3-dimensional computed tomography lung simulation before video-assisted thoracoscopic anatomic segmentectomy for ground glass opacity in lung. J Thorac Dis 2018;10:6598-605. [Crossref] [PubMed]
4. Hagiwara M, Shimada Y, Kato Y, et al. High-quality 3-dimensional image simulation for pulmonary lobectomy and segmentectomy: results of preoperative assessment of pulmonary vessels and short-term surgical outcomes in consecutive patients undergoing video-assisted thoracic surgery†. Eur J Cardiothorac Surg 2014;46:e120-6. [Crossref] [PubMed]
5. Wang X, Wang Q, Zhang X, et al. Application of three-dimensional (3D) reconstruction in the treatment of video-assisted thoracoscopic complex segmentectomy of the lower lung lobe: A retrospective study. Front Surg 2022;9:968199. [Crossref] [PubMed]
6. Cannone G, Verzeletti V, Busetto A, et al. Three-Dimensional Imaging-Guided Lung Anatomic Segmentectomy: A Single-Center Preliminary Experiment. Medicina (Kaunas) 2023;59:2079. [Crossref] [PubMed]
7. Nomori H, Okada M. Illustrated anatomical segmentectomy for lung cancer. Springer Science & Business Media; 2012.
8. Decaluwe H, Petersen RH, Hansen H, et al. Major intraoperative complications during video-assisted thoracoscopic anatomical lung resections: an intention-to-treat analysis. Eur J Cardiothorac Surg 2015;48:588-98; discussion 599. [Crossref] [PubMed]
9. Seguin-Givelet A, Grigoroiu M, Brian E, et al. Planning and marking for thoracoscopic anatomical segmentectomies. J Thorac Dis 2018;10:S1187-94. [Crossref] [PubMed]
10. Xie Z, Zhu X, Li F, et al. Pulmonary Arterial Anatomical Patterns: a Classification Scheme Based on Lobectomy and 3D-CTBA. Thorac Cardiovasc Surg 2024;72:557-67. [Crossref] [PubMed]
11. BOYDEN EA. SCANNELL JG. An analysis of variations in the bronchovascular pattern of the right upper lobe of 50 lungs. Am J Anat 1948;82:27-73. [Crossref] [PubMed]
12. Gonlugur U, Efeoglu T, Kaptanoglu M, et al. Major anatomical variations of the tracheobronchial tree: bronchoscopic observation. Anat Sci Int 2005;80:111-5. [Crossref] [PubMed]
13. Chen ZH, Chu XP, Zhang JT, et al. The regularity of anatomical variations of dominant pulmonary segments in the right upper lobe. Thorac Cancer 2023;14:462-9. [Crossref] [PubMed]
14. Xu H, Zhao H, Jin J, et al. An atlas of anatomical variants of subsegmental pulmonary arteries and recognition error analysis. Front Oncol 2023;13:1127138. [Crossref] [PubMed]
15. Yoldas B, Gursoy S. A pulmonary vascular variation to be considered in resective lung surgical procedures. Ann Thorac Surg 2014;97:715. [Crossref] [PubMed]
16. Xu T, Ye H, Chen W, et al. Abnormal origin of the right posterior segmental bronchus: case report and literature review. J Cardiothorac Surg 2023;18:230. [Crossref] [PubMed]
17. Liu J, Zhan B, Chen Z, et al. Thoracoscopic right upper lobectomy in a patient with displaced posterior segmental bronchus and vascular abnormalities: a case report. Acta Chir Belg 2024;124:325-8. [Crossref] [PubMed]
18. Nagashima T, Shimizu K, Ohtaki Y, et al. Analysis of variation in bronchovascular pattern of the right middle and lower lobes of the lung using three-dimensional CT angiography and bronchography. Gen Thorac Cardiovasc Surg 2017;65:343-9. [Crossref] [PubMed]
19. Brunelli A, Decaluwe H, Gonzalez M, et al. European Society of Thoracic Surgeons expert consensus recommendations on technical standards of segmentectomy for primary lung cancer. Eur J Cardiothorac Surg 2023;63:ezad224. [Crossref] [PubMed]