Abstract
Pulmonary sequestration (PS) is a rare congenital malformation, which mainly contains two variants involving extralobar and intralobar sequestrations. Extralobar sequestrations (ELS) are isolated from the remaining lung tissue and have their visceral pleura. Herein, we report the first case of a torsed ELS associated with congenital lobar emphysema. We described a boy who mainly presented with abdominal and chest pain. A contrast-enhanced computed tomography (CT) scan revealed a mildly enhanced posterior mediastinal mass with left lower lobar emphysema. Thoracoscopic surgery identified a dark and hemorrhagic mass that was connected to the thoracic aorta by a twisted feeding vessel and had its visceral pleura. Pathological findings were consistent with an ELS that had undergone torsion and infarction. The postoperative recovery was uneventful. For the left lower lobar emphysema, he was required for a regular outpatient follow-up. In conclusion, although extremely rare, physicians should maintain a high index of suspicion for torsed ELS when a posterior mediastinal mass with abdominal or chest pain is presented in children.
Introduction
Pulmonary sequestration (PS) is a rare congenital malformation, in which a cystic mass of the lung tissue is nonfunctioning and lacks communication with the tracheobronchial tree. 1 PS receives its blood supply from the systemic circulation, including the thoracic aorta, abdominal aorta, or other vessels. 2 PS mainly contains two variants involving extralobar and intralobar sequestrations, and extralobar sequestrations (ELS) are less common. ELS are isolated from the remaining lung tissue and have their visceral pleura. 3 Most ELS, which are usually asymptomatic or discovered on routine chest x-ray films, are diagnosed prenatally or during the first year of life. 3 Torsion of ELS is an extremely rare entity, and a definite diagnosis is difficult. 4 Herein, we report a very rare case with a torsed ELS and congenital lobar emphysema.
Case presentation
A previously fit 11-year-old boy presented with a 1-week history of abdominal and chest pain, and symptoms worsened for 1 day. He developed a fever of 38.5°C after he was transferred to our institution. His parents denied any other associated diseases. Physical examinations revealed tenderness in his left flank and chest. He was also noted to have decreased breath sounds at the left lung base. His abdominal and chest pain was found to be deteriorated critically by lying down. A routine blood test (RBT) revealed that the white blood cells were 16,900/μL (88.2% neutrophils), hemoglobins were 130 g/L, and C-reactive protein (CRP) was 65 mg/L. Chest and abdominal computed tomography (CT) scan without contrast-enhanced were ordered immediately. Chest CT scan revealed a paraspinal mass in the left posterior mediastinum (Figure 1(a)) and overinflation in the left lower lobe (Figure 1(b)). Pleural effusion was also noted in the left thorax. There were no significant findings on the abdominal CT scan. Therefore, a posterior mediastinal tumor associated with pulmonary infection was considered. Differential diagnoses included congenital pulmonary airway malformation, neuroblastoma, diaphragmatic hernia, or tuberculosis. Upper gastrointestinal contrast study excluded diaphragmatic hernia. Further examinations such as sputum culture and γ-interferon release test were negative. Serous carcinoembryonic antigen (CEA), α-fetoprotein (AFP), and neuron-specific enolase (NSE) were also negative. Following the administration of piperacillin/tazobactam for 3 days, his abdominal and chest pain were dramatically relieved, and his fever also subsided. His RBT turned out to be negative after antibiotic therapy. To clarify the characteristics of the posterior mediastinal mass, a contrast-enhanced chest CT scan was conducted. The paraspinal mass was mildly enhanced without significant feeding vessels (Figure 2(a)), and congenital lobar emphysema was considered in the left lower lobe (Figure 2(b)).
Emergency chest CT scan findings after admission. (a) Chest CT revealed a paraspinal mass in the left posterior mediastinum (black asterisk) and pleural effusion (white arrowhead). (b) Chest CT revealed overinflation in the left lower lobe (white asterisk) and pleural effusion (black arrowhead).
Contrast-enhanced chest CT scan findings following antibiotic therapy.
Subsequently, this patient underwent video-assisted thoracoscopic surgery (VATS). A 5 × 4 × 4 cm triangular mass covered by visceral pleura with a dark and hemorrhagic appearance was found above the diaphragm (Figure 3(a)). A moderate amount of hemorrhagic pleural effusion was also noted. Severe inflammation and adhesions were observed around the lesion. After isolating the mass from the surrounding tissues, we noticed that the mass was connected to the thoracic aorta by a twisted feeding vessel (Figure 3(b)). The twisted feeding vessel was clamped and divided. A chest tube was left after the operation, and it was removed 3 days later. Postoperative pathology identified infarcted and hemorrhagic lung tissues with cartilages and alveoli. The diagnosis was consistent with an ELS that had undergone torsion and infarction.
Thoracoscopic findings of this patient. (a) A triangular mass with a dark and hemorrhagic appearance was found above the diaphragm, and the mass had its visceral pleura. (b) The mass was connected to the thoracic aorta by a twisted feeding vessel (white arrow).
The postoperative recovery was uneventful. For the left lower lobar emphysema, he was required for a regular outpatient follow-up.
Discussion
Congenital lung malformations (CLMs) are a wide spectrum of congenital pulmonary abnormalities involving congenital pulmonary airway malformation, PS, congenital lobar emphysema, and bronchogenic cyst. 5 PS accounts for about 6% of all CLMs, and PS can be associated with other CLMs.2,3 In this case, a torsed ELS associated with congenital lobar emphysema was diagnosed simultaneously. To the best of our knowledge, this is the first reported case with a torsed ELS and congenital lobar emphysema.
A search of the current literature was performed to review the reported torsed ELS in children (Table 1). A total of 17 children with torsed ELS were reported in the literature.1,3,4,6–15 The operative age ranged from 3 to 15 years of age, but most children were diagnosed at school age. The most frequently presented symptom was abdominal pain, and chest pain was noted in over half of all patients. Inflammation of the diaphragm and pleura due to torsion of ELS can lead to severe abdominal and chest pain since ELS is usually located between the left lower lobe and the diaphragm. 3 Torsion of ELS was more common in the left thorax.1,3,4,7–12,14,15 Contrast-enhanced CT scan was the most commonly used examination for the diagnosis of torsed ELS. Generally, the demonstration of a dominant feeding vessel suggests the diagnosis of ELS. However, the lack of typical findings delays definite diagnosis and leads to misdiagnosis. Torsion of the vascular pedicle prevents visualization and resulted in atypical CT findings. Based on our literature review, feeding vessels were only identified in two cases.4,14 In a recent study, Ti et al. 4 reported the main CT signs of torsed ELS: lesions with no enhancement or only mild enhancement, unclear feeding vessels, and a rapid increase in pleural effusion or the size of lesions. Using magnetic resonance imaging (MRI), the diagnosis of torsed ELS could be determined preoperatively in selective cases.13,15 Chest ultrasonography was also effective to detect pulmonary lesions and pleural effusion.9,12 In recent years, VATS has been gradually used for torsed ELS resection.1,3,4,8,9,10–15 Due to the difficulties of preoperative diagnosis of torsed ELS, VATS can provide direct visualization. Using VATS, we found that the mass was connected to a vascular pedicle and had its visceral pleura in this case. The definite diagnosis of torsed ELS was eventually determined based on the operative findings and postoperative pathology. We believed that the paraspinal mass should be resected since tumor could not be excluded completely. However, the associated lobar emphysema was not resected concomitantly. Conservative treatment was conducted because the lobar emphysema was asymptomatic without respiratory distress and his development was not compromised. Lobectomy is considered only for patients with severe and progressive findings. 16 However, close follow-up is recommended considering that clinical symptoms may progress and surgery is possibly required. 17
Characteristics of children with torsed ELS in the literature and current study.
CLM, congenital lung malformations; CT, computed tomography; ELS, extralobar sequestration; MRI, magnetic resonance imaging; PET, positron emission tomography.
Conclusion
In conclusion, although extremely rare, physicians should maintain a high index of suspicion for torsed ELS when a posterior mediastinal mass with abdominal or chest pain is presented in children. Though a systemic feeding vessel is the hallmark of ELS, this is often unidentifiable on imaging in the setting of torsion. ELS can be found with congenital lobar emphysema which warrants long-term follow-up.
