CYTOCHEMICAL AND IMMUNOCYTOCHEMICAL STUDIES Of THYROID PEROXIDASE’ EXPRESSION IN PREOPERATIVE DIAGNOSIS OF THYROID PAPILLARY CARCINOMA AND ITS RADIOIODINE RESISTANT METASTASES
Objective: determination of thyroid peroxidase’ (TPO) expression in punctates of thyroid gland tumors (TG) and postoperative metastases of papillary thyroid cancer; comparison of the effectiveness of cytochemical and immunocytochemical methods for determining the expression of enzyme to surgical intervention for prediction of radioiodine resistance of the mentioned type of carcinoma. Object and methods: immunocytochemical and cytochemical investigations were performed on the material of aspiration puncture biopsies in 30 patients with malignant and 33 with benign thyroid tumors, as well as in the study of 20 metastases detected after thyroidectomy and radioiodine therapy (10 — radioiodine susceptible, 10 — radioiodine resistant metastases). An indirect immunoperoxidase method was used using McAB to TPO. The benzidine method modified by the authors was used for cytochemical detection of TPO activity. Results: with our adapted cytochemical method of detection of TPO activity in punctates, it has been proved that in most benign tumors all epithelial cells exhibited this activity. On the contrary, none of the carcinomas studied did not meet, at which point this activity would have all epithelial cells. This suggests that the method of cytochemical detection of TPO activity in FNA smears is useful in preoperative cytological differential diagnosis of thyroid tumors. Pretty high indicators of accuracy of positive prediction (100%), specificity (88%) and sensitivity (70%) of the method indicate its usefulness. The results of TPO expression in papillary thyroid carcinoma metastases detected in the postoperative period, obtained using cytochemical and immunocytochemical methods, coincide and demonstrate that both methods may be suitable for preoperative prediction of radioiodine resistance of papillary thyroid carcinoma. Conclusions: modification of the cytochemical determination of TPO activity in the epithelium of punctates is effective in the differential cytological diagnosis of malignant and benign thyroid tumors. The coincidence of the results of cytochemical and immunocytochemical methods for the investigation of TPO expression in epithelium of punctates of postoperative radioiodine resistance and radioiodine-sensitive metastases substantiates the possibility of using both methods in preoperative prediction of radioiodine resistance of papillary thyroid carcinoma.