After immunostaining, the spindle tumour cells were positive for cytokeratin AE1/AE3, CAM5.2 and paired box gene 8 (PAX8) and negative for epithelial membrane antigen (EMA), Tg, carcinoembryonic antigen (CEA), thyroid transcription factor-1 (TTF-1), and p53. This evidence concerns the gene PAX8 and neoplasm.