Prevalence of thoracic anatomical variations and congenital anomalies on chest radiographs in a large adult population

Aims: Thoracic anatomical variations and congenital anomalies are usually incidental findings on chest radiographs but may have important implications for diagnosis, interventional procedures, and surgical planning. Epidemiological data on their prevalence in large adult populations, particularly from Turkiye, remain limited. The aim of this study is to strengthen the epidemiological evidence regarding the adult population in Turkiye and to provide a reference dataset that is comparable with radiologic variation data reported in the international literature. Methods: In this retrospective cross-sectional study, digital posteroanterior chest radiographs of 34,445 adults. Thoracic anatomical variations and congenital anomalies detectable on chest radiographs (azygos lobe, right aortic arch, hiatal hernia, Chilaiditi sign, situs inversus totalis, and cervical rib) were systematically evaluated by two pulmonology specialists using Picture Archiving and Communication System (PACS). Results: Thoracic anatomical variations and congenital anomalies were identified in 423 of 34,445 patients (1.2%). The most common finding was an azygos lobe (0.9%), followed by hiatal hernia (0.2%), while right aortic arch, cervical rib, Chilaiditi sign, and situs inversus totalis were rare. Azygos lobe was significantly more frequent in males, whereas hiatal hernia and cervical rib were significantly more frequent in females (p