ABSTRACT
<p><b>OBJECTIVE</b>To study Twist expression in thyroid papillary carcinoma (PTC) by immunohistochemistry and to assess its usefulness as marker in the differential diagnosis of PTC, follicular adenomas (FA) and benign papillary lesions (BPL).</p><p><b>METHODS</b>Fifty cases of PTC, 48 cases of FA and 47 cases of BPL were evaluated using manual tissue chip and SP immunohistochemical stain to detect the expression of Twist and HBME-1, and comparing the staining to that of cytokeratin 19 (CK19).</p><p><b>RESULTS</b>In PTC, positive rates of Twist, HBME-1 and CK19 were 100% (48/48), 94.0% (47/50) and 78.0% (39/ 50) respectively; in FA, positive rates were 0, 6.7% (3/45) and 0 respectively; in BPL, positive rates were 7.0% (3/34), 2.1% (1/47) and 0, respectively. The differences between PTC and FA and between PTC and BPL were both statistically significant (P = 0. 000). The sensitivity of Twist, HBME-1 and CK19 was 100%, 94.0% and 78.0%; the specifity was 96.4%, 95.7% and 100%; overall accurary was 97.7%, 95.1% and 91.9%, respectively.</p><p><b>CONCLUSIONS</b>Positive rates of Twist is higher than the other markers in PTC. Immunohistochemical staining of Twist has important significance in the differential diagnosis of thyroid lesions. Twist immunohistochemistry maybe helpful in diagnosis and differential diagnosis of PTC.</p>