Abstract
Carcinoma arising from a thyroglossal duct remnant (TDR) is relatively rare. We report a case of papillary carcinoma occurring concurrently in the thyroglossal duct cyst and thyroid.
A 51-year-old male visited our hospital with a right supraclavicular fossa mass. CT scanning revealed masses which were present in the midline of his anterior neck and bilateral thyroid lobe. Aspiration biopsy of the cervical lymph node was positive for papillary carcinoma, so TMN classification was considered cT3 (m) N1bM0. A Sistrunk procedure was performed in addition to both a total thyroidectomy and a left neck dissection. Histopathological examination of the surgical specimen showed papillary carcinoma in the thyroglossal duct cyst and in the bilateral thyroid lobe. There were seven cervical lymph node metastases. The patient was discharged without complications.
The problem in this case was whether the carcinoma in the TDR was a primary or a metastatic lesion. The MIB-1 monoclonal antibody reacts with an antigen present within the nuclei of all proliferating cells, but it is absent in the nuclei of quiescent cells. It has been reported that immunohistochemical investigation using the antibody MIB-1 provides useful information on the growth of thyroid lesions. Therefore, we performed an examination immunohistochemically using a monoclonal antibody MIB-1 and assessed the proliferative ability of the tumors. If the MIB-1 labeling index in carcinoma is similar, it will probably indicate a similar cell proliferative ability.
The result was that the papillary carcinomas in the thyroid gland and the metastatic lymph nodes showed average MIB-1-positive cell rates (about 2%), but the carcinoma in the TDR was negative for MIB-1 staining. Also, there was a considerable difference between the cell proliferation of papillary carcinoma in both the TDR and the thyroid gland, and this suggests the possibility that these were multiple primary papillary carcinomas in both the TDR and the thyroid gland.
