Pleural effusion in patients with differentiated papillary thyroid cancer.

Among 1,772 patients who registered at the MD Anderson Cancer Center between 1944 and 1991 with papillary thyroid cancer, 10 had malignant pleural effusion that developed during the course of the disease. At primary surgery, all 10 were found to have metastases to cervical lymph nodes. Seven of these patients also had invasion into adjacent soft tissues, 4 had lung metastases, and 1 had pleural effusion. All patients had radiologically apparent lung metastases at the time pleural effusion was found. Malignant effusion appeared 0 to 60 months after abnormal chest radiographs in 9 patients and 61 to 132 months after the initial diagnosis of thyroid cancer in 4 patients. Pleural effusions were treated with local radioisotopes or sclerosing agents, systemic radioiodine or chemotherapy, or both. All 10 patients died of thyroid cancer; overall survival time was 7 to 170 months (median, 27 months); however, appearance of pleural effusion preceded death by 1 to 20 months (median, 11 months). Malignant pleural effusion complicates the clinical course in 0.6% of adult patients with papillary thyroid cancer. It may develop many years after the initial diagnosis but is associated with greatly shortened survival time in all cases.