Odd lobe is a rare type of anatomical variant of the lung, which is caused by the abnormal migration of the odd vein during embryonic development, separating the upper lobe of the right lung into two parts at the apex of the lung, and causing the local dirty wall layer to fall into it. The odd parietal fissure is composed of two dirty layers and two wall layers of pleura, mostly from the right pulmonary apex inward to the pulmonary hilum, and ends in an inverted comma shape. If the odd vein compresses the bronchus supplying the odd lobe tightly, pulmonary atelectasis and bronchial dilatation may occur in the odd lobe. (The normal odd vein reaches the height of the 4th thoracic vertebra and forms an archofazygosvein (odd vein arch) that turns anteriorly and crosses the superior border of the right pulmonary root to inject into the superior vena cava.)