Papillary and undifferentiated thyroid carcinoma presenting as a metastatic papillary serous effusion. A case report

Papillary carcinoma of the thyroid pursues a long course of local nodal metastases and rarely leads to death. This case reports an occult thyroid tumor which presented as a serous effusion with pure papillary carcinoma. At autopsy, both papillary and undifferentiated carcinoma were found in the thyroid. Although the pleural component was papillary, the fulminant course was that of an undifferentiated carcinoma.