NKX2-1 and thyroid cancer: Metastatic thyroid cancer is immunohistochemically defined by a positive finding for thyroglobulin and thyroid transcription factor 1.33 Including our case, immunohistochemical studies were positive for thyroglobulin in 18 cases5-11,14,16,17,19,20,22,24,26,27 and for thyroid transcription factor 1 in 17 cases.7,8,11,14-22,24,26-28 Thirteen cases were positive for both markers.7,8,11,14,16,17,19,20,22,24,26,27 Information on both markers was not reported in 6 cases (Table 3).