[A clinicopathological study of multiple thyroid carcinomas]

Thyroid cancers associated with multiple cancerous lesions that were detected by clinical and/or histological examination, namely, multiple thyroid carcinomas have been studied clinicopathologically. Of 443 cases of primary thyroid cancers, 111 (25%) had multiple cancerous lesions. Histologically, most multiple cancers consisted of papillary carcinomas. In 66% of the cases, the size of the second cancer was 1.0 cm or less. Fifty-three percent of multiple cancers were located in both the right and left thyroid lobes. Therefore, it is important to examine the contralateral lobe at operation to be certain that there are no other nodular lesions. Since lymph node metastasis was positive in 83% of the cases, it is necessary to perform bilateral neck dissection in multiple cancer cases of not only the bilateral but also of the unilateral type.