Extralobar pulmonary sequestration: A case report and literature review.

Pulmonary sequestration is a congenital malformation of lung development in which part of the lung tissue is separated from the normal lung during the embryonic phase and develops separately and receives blood supply from an aberrant systemic artery forming a nonrespiratory mass. In brief, early in embryonic development, certain tissues that should have atrophied and been gradually absorbed are left behind due to impairment of the atrophy process and form anomalous branches of the aorta, which pull parts of the lung tissue, isolating them from normal lung tissue and bronchi, and thus forming separate lung tissue. According to the relationship of the mass to the pleural covering, pulmonary sequestration can be divided into two types, intralobar pulmonary sequestration (ILS) and extralobar pulmonary sequestration (ELS), of which approximately 75% of cases are ILS, but ELS is less common. Symptoms are not obvious in either type, making diagnosis and differential diagnosis more difficult. Here we report a 33-year-old patient with only insignificant abdominal distension who was eventually diagnosed with retroperitoneal ELS.