Abstract

To evaluate the clinical and histopathological significance of the proliferative activity in neoplastic and non-neoplastic thyroid lesions, we analyzed the mitotic count and the proliferating cell nuclear antigen labeling index (PCNA-LI) by immunohistochemistry as the proliferation- related markers. In this study included were surgically removed normal thyroid tissue (27 cases), adenomatous goiter (15 cases), Hashimoto's thyroiditis (5 cases), follicular adenoma (13 cases), follicular carcinoma (7 cases), papillary carcinoma (44 cases), poorly differentiated carcinoma (2 cases) and undifferentiated carcinoma (3 cases). The median PCNA-LI was 0 in normal thyroid tissue, 0.5 in adenomatous goiter, 6.2 in Hashimoto's thyroiditis, 1.2 in follicular adenoma, 4.8 in follicular carcinoma, 8.5 in papillary carcinoma, 60.8 in poorly differentiated carcinoma, and 55.2 in undifferentiated carcinoma (p=0.0001). Although PCNA-LI was exceptionally high in Hashimoto's thyroiditis, it was suggested that PCNA-LI could be used as a marker differentiating benign lesions from malignant neoplasm. Also, it could differentiate follicular adenoma from follicular carcinoma. Except clinical stage (p=0.0397), PCNA-LI was not related with sex, size, histologic subtype, and lymph node metastasis in papillary carcinoma. The presence of mitosis differentiated the neoplastic thyroid lesions from the non-neoplastic lesions (p<0.05), however, it could not divide benign and malignant neoplasm. These results suggest that an evaluation of the proliferative activity can help to differentiate the thyroid lesions. In addition, there was no significant correlation between the value of PCNA-LI and the presence of mitosis. It can be recommended to evaluate both the mitotic count and the PCNA-LI for determining the proliferative activity of the thyroid lesions.

• Keywords: Thyroid;Mitotic count;PCNA labeling index;Papillary carcinoma;