Bronchogenic cyst with high carbohydrate antigen 19-9 in the cyst fluid and the serum

A mass of 8 cm in diameter was revealed in the right upper lung field of a 46-year-old female patient. The chest X-ray film taken one year previously revealed only a linear shadow in the same position, which was thought to be a vacant cyst. The levels of carbohydrate antigen (CA) 19-9 in cyst fluid and serum were elevated, at 410,000 and 130 U/ml, respectively. After surgical resection, serum CA19-9 returned to normal. Pathologically, the cyst wall was lined with bronchial epithelium with no evidence of malignancy. Immunohistochemical study revealed CA19-9 positivity in the bronchial epithelium of the cyst wall.