Background
Primary disease in thorax associated with an azygos lobe is extremely rare. It is usually identified incidentally on chest X-ray or CT during health checkups with an incidence of up to 0.2%. This is the first study involving 46 of patients found with azygos lobe in surgery of English literature from January 1931 to October 2018.
Methods
PubMed, EMBASE and the Web of Science databases were searched for full-text literatures met out inclusion criteria. We summarized the clinical data, radiological manifestation, accompanying disease and treatment strategy of all patients.
Results
18 eligible studies involving 46 patients were selected for this research. The mean age was 36.5 years old. There were 26 male patients and 20 female patients and the male to female ratio nearly to 1.3:1. There were many different primary diseases with azygos lobe including lung cancer (n = 8), spontaneous pneumothorax (n = 5), esophageal cancer (n = 1), pulmonary sequestration (n = 1), esophageal atresia (n = 2), hyperhidrosis (n = 29). The azygos lobe (azygos lobe in Figs. 1 and 2) is an uncommon anomaly that is found in 1% of anatomic specimens, on about 0.4% of chest radiographs and 1.2% of high resolution CT. The azygos lobe is a developmental anomaly but not a true accessory lobe. Azygos lobe of all patients was diagnosed during the operation.
Conclusions
Azygos lobe occurs in 0.2% of the population and can make clinical diagnosis difficult. The detection of this anomaly and clarification of its precise anatomical features are important to alert the surgeon to potential problems during surgery.