Pulmonary sequestration in adult patients: a single-center retrospective study

PS is the second most common congenital lung malformation, accounting for 0.15–6.45% of all congenital lung malformations, with an incidence of about 1/20,000 in the population [7]. PS can be divided into intralobar and extralobar types depending on the presence or absence of a separate visceral pleura covering the lung parenchyma and venous drainage. Intralobar PS is commonly seen in the age group of 20 years and younger, but rarely diagnosed at age 50 or older [8]. A case series study from Mayo Clinic included 32 adults PS patients with a median age of 42 years (IQR 28–53) [6]. To the best of our knowledge, this is a single-center study with the largest sample size analyzing the clinical and imaging characteristics and surgical outcomes in adult PS to date. 97 adult PS patients were included in the study, with a median age of 38 years (interquartile range 29–48).

PS may present with cough, sputum, hemoptysis, fever, chest pain, and chest tightness, when accompanied with pulmonary infection [1]. PS can be asymptomatic and diagnosed incidentally when there is no pulmonary infection [9, 10]. In our study, 22.7% of patients did not complain of any specific symptoms and were found incidentally by CT scans of the chest during health examination.

Contrast-enhanced CT scans show that PS can present with a variety of different manifestations including masses, cysts, bronchiectasis or pulmonary atelectasis [3]. Sun et al. reported that the most common CT findings of PS were soft tissue shadow, cystic lesions, cavitary lesions and bronchiectasis [9]. Alsumrain et al. reported that masses/solid lesions (61% of cases) were the most common CT findings of PS [6]. Our study showed that the most common CT findings were mass lesions (50.5%) followed by cystic lesions (20.6%), cavitary lesions (10.3%), pneumonic lesion (6.2%), bronchiectasis (6.2%), and intrapulmonary cord-like shadow (6.2%).

The definite diagnosis of PS requires the identification of abnormal arterial supply to the sequestered lung tissues [11]. By searching the Chinese National Knowledge infrastructure (CNKI) database, Wei et al. found that the thoracic aorta (1384 cases, 76.55%) and the abdominal aorta (334 cases, 18.47%) were the two most common sources of arterial supply. The number of arterial supplies included one (79.09%), two (15.99%) and more than two (4.92%). Our findings were similar to their outcomes, showing that the arterial supply was mainly originated from the thoracic aorta (87.4%), followed by the abdominal aorta (10.5%). There were only one supplying artery in 80 (82.5%) cases, two in 12 (10.5%) and three in 5 (5.1%). It has been reported that the vast majority of venous drainage in intralobar PS was into the pulmonary veins [12]. For extralobar PS, however, it was drained into systemic veins, frequently inferior vena cava, azygos vein, or hemiazygos vein [13]. Our study showed that all of the PS veins reflowed to the pulmonary veins except for two (2.1%) vein that drained to the azygos vein (one for intralobar PS and one for extralobar PS) and one (1%) to the inferior vena cava (intralobar PS).

Although no established guidelines have been generated so far for the treatment of PS, it has been generally accepted that surgical resection is the preferred therapy modality for PS in most patients, regardless of the presence of symptoms [13, 14]. Surgical treatment can achieve the following objectives: removal of the lesion, definite confirmation of the diagnosis, avoidance of complication occurrence and controversial tumor formation [14, 15]. In recent years, VATS has gradually become the preferred treatment modality for PS due to the advantages of less postoperative pain, more aesthetics, and faster recovery [16]. The advantages and disadvantages of minimally invasive surgery versus open thoracotomy have been previously explored [17]. Wang et al. found that although there were no significant differences in operative time, postoperative hospital days, or complication rates, minimally invasive surgery had less intraoperative bleeding compared to open thoracotomy, but more postoperative drainage volume and longer duration of chest drainage. Liu et al. revealed that no significant differences were found between video-assisted thoracic surgery group and open thoracotomy group in terms of the duration of operation, blood loss, amount of chest drainage, duration of chest drainage, length of postoperative hospital stay, and complications [18]. Our results showed that there were no significant differences between the two groups in terms of operative time (P = 0.133). However, minimally invasive surgery was associated with less intraoperative blood loss (P = 0.001), less drainage volume (P = 0.004), shorter postoperative hospital days (P = 0.017) and shorter duration of chest drainage (P = 0.001), suggesting minimally invasive surgery as a safe and effective treatment modality in the treatment of PS.

Lobectomy is the recommended treatment for intralobar PS [16]. However, in terms of lung function preservation, sublobar resection is an alternative modality to lobectomy for peripheral lesions or small asymptomatic lesions [19]. In our study, segmentectomy and wedge resection was performed in two (2.1%) and four (4.1%) patients of intralobar PS, respectively. All of these patients complained complete remission and no recurrence during the follow-up visits (median follow-up period was 26 months). Dissection of the abnormal vessels only may be enough for intralobular PS with only hemoptysis and no symptoms of pulmonary infection [16]. Two patients in this study complained of hemoptysis only and preoperative CT scans showed intrapulmonary cord-like shadow, with no evidence of inflammation. They both underwent supplying artery dissection only, with complete remission and no recurrence during the follow-up visit (30 months and 19 months, respectively).

We acknowledge there are several limitations of this study needed be considered. First, this study involved a single center and was retrospective by design. Selection bias may have existed. Second, high follow-up lost rate (30 of 97, 30.9%) and relatively short follow-up period resulted in incomplete prognostic information of these patients.