Thyroid Gland as a Target of Secondary Malignancies - an Autopsy Study and Review Data

Abstract

Secondary malignancies of the thyroid gland are rarely diagnosed but their incidence at autopsy is not uncommon. To investigate the clinicopathological features of patients with metastatic tumours of the thyroid gland, we reviewed autopsy records and pathological features of 36 cases with thyroidal secondary tumours from 266 cases of malignant neoplasias (excluding cases of primary thyroid cancer), over a 16-year period. There were 19 men and 17 women in the study, ranging in age from 37 to 95 years (mean 70.4 years). The incidence of metastasis in thyroid gland was 0.9% in all autopsy cases, and 13.53% of the malignant tumours. The majority were carcinomas of epithelial origin. The lung was the most common primary tumour site (33.3%), followed by the breast (8.33%) and the kidney (8.33%). The most common non-epithelial malignancy was lymphoma, followed by leukaemia (total of both 25%). As for the microscopic morphological observations, diffuse infiltration pattern of tumour cells was noted in 63.89% of the cases, the formation of nodules in 33.33% of the cases and contiguous invasion in 2.79% of the cases. There were 35.71% cases of metastases associated with multinodular goitre and 28.57% cases associated with papillary microcarcinoma. Our study indicates that thyroid secondary malignancies are not infrequent and may constitute a diagnostic problem. Lung cancer is the most common neoplasm that metastasizes to the thyroid gland in north-western Greek population.