NKX2-1 and neoplasm: Immunohistochemically, the tumor cells were positive for paired-box gene 8 (PAX8) (EPR13510, Abcam, Cambridge, UK) (Fig. 5a) and thyroid transcription factor-1 (TTF-1) (8G7G3/1, Dako, Carpinteria, CA, USA) (Fig. 5b).