IMMUNOHISTOCHEMICAL ASPECTS OF AUTONOMOUSLY FUNCTIONING THYROID NODULES (AFTNs)

The immunohistochemical aspects of 18 patients with autonomously functioning thyroid nodules (AFTNs) examined between 1984 and 1988 are investigated. The diagnosis of AFTN is made by the thyroid scintigraphy, which shows increased radioiodine uptake (hot nodule). Histologically, follicular adenoma was present in 5 patients and adenomatous goiter in 13.For the immunohistochemical investigations, paraffin sections were stained for thyroglobulin (Tg), thyroxine (T4), and triiodothyronin (T3) using the avidin-biotin peroxidase complex method. The positivity for Tg, T3 and T4 was found to be stronger in AFTN tissues than in the extranodular thyroid tissues. In particular, they were strongly positive in the areas of papillary structure and microfollicles, or some eosinophilic cells in the foci of lymphocyte infiltration associated with focal thyroiditis. In conclusion, the immunohistochemical examination of T3, T4 and Tg is useful for differentiating AFTN from a nonfunctioning nodule or carcinoma of the thyroid.