Role of basic fibroblast growth factor in the pathogenesis of nodular goiter

Thyroid epithelial cells are known to produce several growth factors and cytokines which influence thyroid cell growth and function in an autocrine and/or paracrine manner. It is already known that insulin-like growth factor I (IGF I) is overexpressed in toxic adenomas whereas epidermal growth factor (EGF) is found predominantly in thyroid neoplasia. We now investigated the expression of bFGF by immunohistochemistry in thyroid tissue of patients with toxic adenoma (n = 27), cold nodules (n = 27) and for comparison in Graves' disease (n = 5). In addition bcl-2-oncoprotein expression in these tissues were also detected by immunohistochemistry. Most of bFGF immunostaining was found in the connective tissue of all thyroid tissues with a predominance in adenomas and in Graves' diseases. The collagen surrounding the thyroid follicles close to their basal membrane were homogeneously and intensively stained. All the cytoplasm of fibroblast in the connective tissue were strongly positive. Within the cytoplasm of only 2-10% thyroid epithelial cells bFGF immunostaining was found without any difference between toxic adenomas or cold nodules. In the tissue of patients with Graves' disease, less than 2% of thyrocytes were stained. All thyroid epithelial cell showed clearly an immunostaining for bcl-2-oncoprotein in nodular goiter as well as Graves' disease.