Metastases from occult thyroid carcinoma. An autopsy study from Hiroshima and Nagasaki, Japan

In an autopsy series in Hiroshima and Nagasaki, Japan, cervical lymph node dissections were performed in 128 autopsy cases in which occult papillary thyroid carcinoma had been found, and metastatic carcinoma was demonstrated in 20 cases (16%). These 20 cases with metastatic carcinoma, and an additional 25 occult papillary thyroid carcinomas previously known to have metastases, were compared with the 108 cases which had lymph node dissections negative for metastatic thyroid carcinoma. Significantly increased lymph node metastases occurred in association with the following changes in the the thyroid gland: multiple tumor foci, larger tumor size, greater tumor invasiveness, more than 50% papillary differentiation, and tumor psammoma bodies. Metastases were significantly more frequent in men than in women. In 5 of the 25 additional cases, only the cervical lymph node metastases and no tumor in the thyroid glands were found at routine autopsy. Special thyroid reexamination revealed the small primary carcinomas. In this autopsy series, no thyroid follicle inclusions have been found in cervical lymph nodes in the absence of a primary thyroid carcinoma. The metastases were generally occult, and sometimes multiple, contralateral, and bilateral. In the entire autopsy series, only one occult thyroid carcinoma was the cause of death; 517 other persons with occult papillary carcinoma of the thyroid reached the end of their lifespan without awareness or manifestation of the presence of the tumor.