Progressive hypereosinophilia with lung nodules due to thyroid carcinoma

An elderly woman had dyspnea, a thyroid mass and multiple lung nodules on chest radiographs. She developed hypereosinophilia over a three-month period in which multiple diagnostic procedures were performed, without definition of the disease process. At post-mortem examination, the primary lesion was found to be a poorly differentiated carcinoma of the thyroid, metastatic to lung. This is the second case of hypereosinophilia related to metastatic thyroid carcinoma. The intensity of the hypereosinophilia in this case was increased by the administration of thyroid-stimulating hormone and by the development of necrosis of the lung nodules.