Introduction. papillary thyroid cancer is increasingly being detected at early stages when regional and distant metastases are absent per clinical examination. However, lymph nodes of the central zone can carry hidden metastases. frequency of such metastases is 22.3–46.7 %. maximally accurate identification of hidden metastases after lymph node dissection remains an important problem.Aim. тo evaluate the effect of histological examination characteristics and immunohistochemical measurement of pancytokeratin level on frequency of detection of papillary cancer hidden metastases in regional lymph nodes of the central zone in patients with clinical stage N0 papillary cancer.Materials and methods. The main group included 50 patients with stage ст1–2N0М0 primary papillary thyroid cancer. Dissected central lymph nodes of the patients prior to formalin fixation were extracted from the sample and inserted in individual paraffin blocks. Apart from standard histological examination, pancytokeratin level was measured immunohistochemically in the lymph nodes. The control group consisted of 200 patients for whom dissected central cell tissue was sectioned into blocks after formalin fixation. The number of lymph nodes in the dissected sample was measured by a pathomorphologist.Results. In the main group, the number of lymph nodes in the sample varied between 6 and 37 with mean of 20.7 ± 6.8; in the control group the number was lower: 3–25, mean 9.8 ± 5.1 (р = 0.000). In the main group, hidden metastases were detected more frequently than in the control group: in 30 (60 %) and 68 (34 %) cases, respectively (р = 0.001). In 20 (40 %) patients, immunohistochemical examination showed new metastases. use of this method allowed to detect 1 to 7 additional metastases (mean 2.4 ± 1.5 lymph node lesions).Conclusion. use of targeted dissection with extraction of lymph nodes led to significant increase in their numbers in the samples, and immunohistochemical examination allowed to detect a large number of hidden metastases in the central lymph nodes.

Background: Papillary thyroid cancer (PTC) course and outcome very much depend on prognosis factors. One of the most significant factors is extrathyroidal extension (ETE), which can be local or extensive. In the view of some authors, tumor grow beyond the thyroid capsule is associated with high risk locoregional and distant metastasis, which increase disease recurrence and reduce survival. Some others do not see influence of minimal ETE on disease prognosis, so we need more trials to clarify the role of ETE in PTC. Aims: To evaluate the ETE role in development of metastasis in PTC patients. Materials and methods: The study includes 233 patients with PTC who receive treatment in RSCRR. 185 patients had clinical N0 stage, 48 patients were with verified N1a1b. All patients with cN0 underwent thyroidectomy with central neck dissection, patients with N1 thyroidectomy combined with different neck dissections, also superior mediastinal lymphadenectomy if required. Within combination treatment the radioiodine therapy was carried out. The histology evaluated thyroid capsule involvement and lymph node metastasis. Data processing was carried out in a Microsoft Access database, a one-factor dispersion analysis was used for the analysis of the quantitative signs, and a -square criterion was used for qualitative ones. Multifactor analysis was done in SPSS20 program. Results: Thyroid capsule extension was detected in 111 cases (47.6%), from which 92 were microscopic. 122 patients did not have ETE. The frequency of lymph node metastasis with or without ETE was 62.2% and35.8% respectively, which is significantly more often (р = 0.000, 2 = 21.342). In microscopic and macroscopic extension regional metastasis were 56.5% and 94.7%, distant metastasis 1.1 and 21% respectively. Statistically significant, the ETE was more prevalent in non-encapsulated tumor cases (р = 0.000, 2=15.122), and if the tumor size was more than 1cm (р = 0.026, 2 = 7.293). Only 41% of patients with cN0 had ETE, and patients with N1 72.9%, which is statistically significant (р = 0.000, 2 = 14.235). Conclusion: ETE is a predictor of PTC metastasis. The presence of ETE requires the necessity to apply the more aggressive treatment of PTC including thyroidectomy with central neck dissection and radioiodine therapy. Gross ETE significantly increases the risk of regional together with distant metastasis.

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Background. The regional lymph node metastasis in differentiated thyroid cancer (DTC) is still very high: 50–60%, especially in papillary form. Averagely, after central neck lymph node dissection (CNLD), in 30–40% cases “hidden” metastasis in lymph nodes of VI zone of neck were revealed. But they were not indicated by preoperative diagnostic procedures: ultrasound (US) and computer tomogpraphy (CT). Aims. To define the factors associated with the increased risk of lymph node metastasis for specification of indications to CNLD performance. Materials and methods. The study covers 105 patients with clinical stages of DTC T1-2N0M0, who received a thyroidectomy (TE) with preventive bilateral CNLD in RSCRR since 2012 till 2017. Patients older than 45 y.o. prevailed (66 patients (62.9%)). Data processing was carried out in a Microsoft Access database, a one-factor dispersion analysis was used for the analysis of the quantitative signs, and a c-square criterion was used for the qualitative ones. Results. The “hidden” metastasizes are founded by 32 (30.5%) patients. Multifocality is registered in 29 (27.6%) cases, lack of the tumor node capsule is registered in 65 (61.9%) and an invasion of the thyroid gland capsule is registered in 38 (36.2%) patients. Background diseases of the thyroid gland (TG) have 69 (65.7%) patients. According to the multifactorial analysis reliable independent predictors of the “hidden” metastasis of central neck lymph nodes were invasion of the anatomic capsule of TG (р = 0.003), age of patients ≤45 y.o. (р = 0.005), nonincapsulated form of tumor (р = 0.007). Conclusion. Use of TE in combination with CNLD allowed to restage at 46.7% of patients due to TG capsule invasion (28.6%) and “hidden” metastasis in VI group lymph nodes (30.5%) identification.