A case of bronchogenic cyst with high production of antigen CA 19-9.

A 35-year-old man was hospitalized with complaints of retrosternal pain and high fever. A chest radiograph showed a large round mass in the mediastinum. Of the several tumor markers in the serum tested, only CA 19-9 was elevated. Thoracotomy revealed a cystic mass with purulent hemorrhagic materials. Histologically the cyst was lined by bronchial epithelium with no evidence of malignancy. The high level of CA 19-9 in the cystic fluid, and positive immunohistochemical staining of the bronchial glands in the cyst wall for CA 19-9 indicated that the elevated serum level of CA 19-9 originated from the bronchogenic cyst after its infection.