Objective To investigate the expression of S100A4 protein in benign and malignant thyroid tissues and its clinical significance. Methods Expression of S100A4 protein in thyroid cancers (50 cases), adenoma (45 cases) and adjacent noncancerous tissue (20 cases) was respectively studied by microwave-LSAB immunohistochemical staining. Results The positive rate of S100A4 protein in thyroid cancer and adenoma was 78.0% and 15.6% respectively. No S100A4 protein expression was found in any adjacent noncancerous tissue (P ＜0. 01). No correlation was observed between expression of S100A4 protein and histological grading of thyroid cancer. Expression of S100A4 protein in lymph node metastasis and staging Ⅲ-Ⅳ was both higher than that in negative cases and staging Ⅰ -Ⅱ (P ＜0. 05). The rate of recurrence and death in S100A4 protein positive cases were notably higher than that in negative cases (P ＜ 0. 05). Conclusions S100A4 protein expression can help to distinguish benign and malignant thyroid tissues. It can be used as a molecular marker to predict thyroid metastasis.

Objective:To investigate CK19 and COX-2 expression in papillary thyroid carcinoma (PTC) and their relationship with clinicopathologic parameters.Methods:Retrospective study of 120 consecutive patients with PTC who underwent resection from May. 2017 to Dec. 2020 was conducted. The expression of CK19 and COX-2 in 120 pieces of primary PTC tissue and 30 pieces of adjacent carcinoma tissue were detected by EliVision TM plus two-step immunohistochemical method. The relationship between the expression of CK19 and COX-2 and the clinicopathologic parameters including patient age, TI-RADS classification, TNM staging, carcinomatous infiltration, lymph node metastasis was studied. The analysis was performed using SPSS 22.0 software. The numerical data were presented as numbers and percentages, and chi-test ( χ2 test) and Pearson’s correlation were used to analyze the difference and association between two groups. P<0.05 was considered statistically significant. Results:The positive immunostaining of CK19 and COX-2 were mainly localized in the cytoplasm. The positive rates of CK19 and COX-2 were 87.50% (105/120) and 72.50% (87/120) in cancer tissues and 10.00% (3/30) and 3.33% (1/30) in paracancerous tissues, respectively, with statistically significant differences (both P<0.05 by χ2 test) . In the groups with patients aged <45 years versus ≥45 years, the CK19 positive rates were 88.16% (67/76) and 86.36% (38/44) , and the COX-2 positive rates were 69.74% (53/76) and 77.27% (34/44) , respectively. In the groups of TI-RADS (grade 4 and 5) versus grade 6, the CK19 positive rates were 85.26% (81/95) and 96.00% (24/25) , and the COX-2 positive rates were 69.47% (66/95) and 84.00% (21/25) , respectively, with no statistically significant differences between the two groups (both P>0.05) . In the groups of TNM (stage T1 and T2) versus stage T3, the CK19 positive rates were 82.28% (65/79) and 97.56% (40/41) , and the COX-2 positive rates were 65.82% (52/79) and 85.36% (35/41) , respectively. In the groups with versus without cancer infiltration, the CK19 positive rates were 94.44% (68/72) and 77.08% (37/48) , and the COX-2 positive rates were 83.33% (60/72) and 56.25% (27/48) , respectively. In the groups with versus without lymph node metastasis, the CK19 positive rates were 95.59% (65/68) and 76.92% (40/52) , and the COX-2 positive rates were 83.82% (57/68) and 57.69% (30/52) , respectively, and the differences between the above groups were statistically significant (all P<0.05 by χ2 test) . The co-positive and co-negative expression rates of CK19 and COX-2 in 120 patients were 70.83% (85/120) and 10.83% (13/120) , respectively, with a positive correlation ( r=0.45, P<0.05 by Pearson’s correlation) . Conclusions:The positive rates of CK19 and COX-2 expressions are not related to patient’s age or TI-RADS classification, but closely related to TNM stage, cancer invasion and lymph node metastasis. The up-regulation of both CK19 and COX-2 expressions predicts higher tumor stage, more aggressive invasion and more prone to lymph node metastasis.