Abstract
Elevated carbohydrate antigen (CA) 19-9 can indicate malignancies of the gastrointestinal, pancreatic, and biliary tracts, and be found in a pulmonary sequestration. A 30-year-old man visited Seoul National University Bundang Hospital due to elevated CA 19-9 levels, representing pulmonary sequestration of the bilateral lower lobes, which were connected with each other. We performed left lower lobectomy and division of the systemic arteries. After operation, CA 19-9 levels decreased to normal range, even though a small amount of sequestrated lung remained in the right lower lobe. It is not uncommon that presence of pulmonary sequestration might elevate serum CA 19-9 levels; however, horseshoe type bilateral pulmonary sequestration is very rare.