Recurrent papillary thyroid carcinoma with pleural metastasis diagnosed by effusion cytology: a report of cases with clinicopathologic correlation.

Papillary thyroid carcinoma (PTC) is typically an indolent disease characterized by slow growth and a favorable prognosis. In rare instances, this disease may metastasize to the pleura and manifest as a malignant pleural effusion. We report 3 female patients of Japanese/Okinawan ancestry with a history of PTC who presented with hydrothorax.