An azygos lobe is a rare anatomic variant of the lung,which forms during the vein penetrates through the upper lobe of the lung and drags the parietal and visceral pleura with it. The lack of understanding leads to the missed diagnosis of azygos lobe. In our study, the azygos lobes of 20 children were not identified in the first imaging examination.
Most studies report that an azygos lobe is not susceptible to disease. Because of the mesoazygos, the azygos lobe may be isolated from pathological processes developing in the rest of the lung tissue, such as the dissemination of pulmonary tuberculosis and other pathogen infection. However, there are still multiple reports about pathological conditions associated within the azygos lobe. Ndiaye reported that the azygos lobe could lead to atelectasis or bronchiectasis if the fissure was too deep to compress the underlying bronchus draining the azygos lobe. Cases of spontaneous pneumothorax, recurrent hemoptysis and cancer (such as azygos vein aneurysm) associated with an azygous lobe have been reported as well. Pathological processes originating in the azygos lobe, such as carcinoma, may be confined to it.
However, the aforementioned reports were all conducted in adults. To the best of our knowledge, the clinical characteristics about children with azygos lobe has not been reported so far. In our study, 14 (28%) patients were found to have azygos lobe incidentally, while the other 36 cases were diagnosed as pulmonary infections. Furthermore, there were no cases of atelectasis, bronchiectasis, pneumothorax and neoplasm associated with the azygos lobe. And the infection of azygos lobe,manifested as patchy opacity (14%) and consolidation (2%), was found in 8 cases, which was different from most previous literature reports. Among them༌3 patients had infection only confined to the azygos lobe, and another 5 patients also had infection of other lung lobes. It was hard to tell whether the infection of the azygos lobe was primary infection or caused by the dissemination of other lung lobe infection. But there were evidences that the azygos lobe also underwent pathological changes, which should not be ignored. To explore risk factors related to the azygos lobe infection, characteristics of those cases with and without azygos lobe infections were compared. However, no significant risk factors were found. The cause of the azygos lobe infection was still unknown.
Interestingly, we found that some cases with the azygos lobe also had other abnormalities including congenital heart disease, Down syndrome, and other respiratory malformations. Whether formation of azygos lobe is related to genetic variation is a question worthy of further exploration.
RRTIs in children remain a great challenge to pediatricians. The causes of RRTIs vary a lot including malnutrition, tobacco exposure, low social-economic status, immunodeficiency, and respiratory malformations are one of the most import causes of RRTIs. In our study, we found 8 patients with azygos lobe had a history of RRTIs. It reminds us that we should consider the existence of azygos lobe when managing children with RRTIs and chest radiology should be conducted in time to confirm the diagnosis.
Azygos lobe does not require special treatment unless it causes significant diseases, such as spontaneous pneumothorax, recurrent infection, cancer, and so on. So far, there are limited reports on the treatment of azygos lobe. Thoracotomy and video-assisted thoracoscopic surgery lobectomy to treat lung cancer originating from azygos lobe were reported. In addition, lobectomy was also recommended in patients with recurrent infection of azygos lobe and spontaneous pneumothorax associated with azygos lobe. In our study, all the children with azygos lobe infection were cured after reasonable anti-infective treatment. However, the long-term prognosis requires further monitoring and study.