Giant hamartoma of the lung with a high production of carbohydrate antigen 19-9.

A rare case of a giant pulmonary hamartoma with a high production of carbohydrate antigen (CA) 19-9 is presented. A 43-year-old woman with complaints of cough, fever, and chest pain was diagnosed as having a posterior mediastinal tumor with pneumonia. The serum CA 19-9 level was high. A thoracotomy revealed an intrapulmonary solid mass with a histologic diagnosis of cartilaginous hamartoma with no evidence of malignancy. The CA 19-9 concentration in the mucus of the tumor was high, and postoperatively the serum CA 19-9 level returned to normal. The CA 19-9 could be immunohistochemically demonstrated on the surface of the tumor.