The Relationship Between Intralobar Pulmonary Sequestration and Type a Aortic Dissection: A Case Report

Background: Pulmonary sequestrations often lead to serious complications such as infections, tuberculosis, fatal hemoptysis, cardiovascular problems, and even malignant degeneration, but it is rarely documented with medium and large vessel vasculitis, which is likely to result in acute aortic syndromes. Case presentation: A 44-year-old man with a history of acute Stanford type A aortic dissection status post-reconstructive surgery �ve years ago. The contrast-enhanced computed tomography (CT) of the chest at that time had also revealed an intralobar pulmonary sequestration in the left lower lung region, and the angiography also presented perivascular changes with mild mural thickening and wall enhancement, which indicated mild vasculitis. The intralobar pulmonary sequestration in the left lower lung region was long-term unprocessed, which was probably associated with his intermittent chest tightness since no speci�c medical �ndings were detected but only positive sputum culture with mycobacterium avium-intracellulare complex and Aspergillus. We performed uniportal video-assisted thoracoscopic surgery with wedge resection of the left lower lung. Hypervascularity over the parietal pleura, engorgement of the bronchus due to a moderate amount of mucus, and �rm adhesion of the lesion to the thoracic aorta were histopathologically noticed. Conclusion: We hypothesized that a long-term pulmonary sequestration-related bacterial and fungal infection can result in focal infectious aortitis gradually, which may threateningly contribute to aortic dissection.


Background
Pulmonary sequestrations are associated with serious complications including bacterial and fungal infections, tuberculosis, massive hemothorax, serious hemoptysis, cardiovascular events, malignant degeneration, and even rarely but fatal medium and large vessel vasculitis.Aortitis as a form of large vessel vasculitis caused mainly by rheumatological in ammation or infection potentially results in acute aortic syndromes, including aortic dissection.We herein present a 44-year-old man with a history of acute Stanford type A aortic dissection status post-reconstructive surgery ve years ago.The patient presented with a long-term unprocessed intralobar pulmonary sequestration in the left lower lung region, which was probably associated with intermittent chest tightness since no speci c medical ndings were detected.Furthermore, sputum culture was positive for mycobacterium avium-intracellulare complex and Aspergillus.We performed uniportal video-assisted thoracoscopic surgery with wedge resection of the left lower lung.Since the patient was relatively young and had no history of systemic hypertension, we hypothesized that a long-term pulmonary sequestration-related bacterial and fungal infection can result in focal infectious aortitis gradually, which may contribute to aortic dissection.

Case Presentation
A 44-year-old man presented to us with a history of acute aortic dissection, Stanford type A with the aortic arch and the carotid arteries involvement (Fig. 1).He had undergone reconstruction of the ascending aorta and the aortic arch up to the branching out of the right innominate artery ve years ago.The contrast-enhanced computed tomography (CT) of the chest at that time had also revealed a focal area of cystic change (Fig. 2A) and patchy consolidation in the medial region of the lower lobe of the left lung.Two aberrant arteries arising from the aorta were supplying this area (Fig. 2B), which was suggestive of an intralobar pulmonary sequestration.CT angiography also revealed perivascular changes with mild mural thickening and wall enhancement, which indicated mild vasculitis (Fig. 2C).At that time, he immediately underwent emergent surgery for the aortic dissection, which could prove to be fatal, but attention was not given to the pulmonary sequestration at that time.Histopathology of ascending aorta intima revealed myxoid degeneration, intimal hyperplasia, and abundant brin and neutrophils.
However, a year ago, he started complaining of chest tightness, intermittently.He was admitted to the department of thoracic medicine to rule out cardiovascular or gastrointestinal pathologies, but no speci c ndings were revealed except for sputum culture, which was positive for mycobacterium aviumintracellulare complex and aspergillus.The patient was then admitted to the department of thoracic surgery to deal with his long-term unprocessed intralobar pulmonary sequestration.We performed uniportal video-assisted thoracoscopic surgery with an extended wedge resection of the left lower lung.
Firm adhesion of the sequestrated lung to the thoracic aorta and the two aberrant arteries originating from the thoracic aorta were identi ed (Fig. 3A) and then resected by Endo GIA.Meanwhile, hypervascularity over the parietal pleura as well as engorgement of the bronchus were also noticed.The macroscopic ndings revealed a solid pulmonary nodule about 10 x 4 x 2 cm 3 in size with focal bronchial dilation containing hemorrhage and mucus (Fig. 3B), calci cation as well as extensive necrosis of the lung.Histopathological analysis revealed small bronchial duct hyperplasia along with two lymph nodes showing reactive lymphoid hyperplasia, with no evidence of malignancy.Postoperative recovery was smooth, without any surgical complications, and the patient was discharged on the 4th postoperative day.

Discussion And Conclusions
sequestrations are bronchopulmonary foregut malformations, usually characterized by a nonfunctional segmental lung tissue that dissociates from the normal tracheobronchial tree or the pulmonary arteries, and commonly appears in the lower lobes of the lung.Pulmonary sequestrations lead to serious complications: fungal infections, tuberculosis (1), fatal hemoptysis, massive hemothorax, cardiovascular problems (2), and even benign or malignant degeneration.Infected pulmonary sequestration due to mycobacteria, such as Mycobacterium tuberculosis and Mycobacterium aviumintracellulare complex, occur rarely.Aortitis, which is de ned as a form of large vessel vasculitis, is characterized by the in ammation of the aortic wall.Most cases of aortitis are either due to rheumatological causes, which include large vessel Figures Figure 1 Type A aortic dissection with intimal ap involving the ascending aorta, the aortic arch (arrow in Fig. 1A) and the common carotid arteries bilaterally.(Fig. 1B) Arrow in Fig. 1B points to the mural thrombus in the false lumen.Video-assisted thoracoscopic surgery revealed that the two aberrant arteries (Fig. 3A, green arrow) originated from the thoracic aorta.Engorgement of the (Fig. 3A, yellow arrow) was also noticed.Gross specimen showed focal bronchial dilation that contained mucus (Fig. 3B, yellow arrow).