Horseshoe lung is a potential finding in congenital pulmonary venolobar syndrome, where the most inferior portion of the right lung passes posterior to the heart, anterior to the aorta and abuts/ joins the left lung in a horseshoe configuration. It has little clinical relevance other than as a hallmark for other important congenital findings such as:

• scimitar vein/syndrome or other forms of partial anomalous pulmonary venous return
• sinus venosus ASD
• pulmonary hypertension
• pulmonary sequestration (systemic vessel supplying the lung)