[Thyroid Transcription Factor-1 is Useful for Identifying Primary Tumors].

: A 67-year-old man had underwent liver resection 3 years previously. The pathological diagnosis was intrahepatic cholangiocarcinoma. However, a follow-up computed tomography(CT) scan revealed gradual enlargement of the pulmonary nodule left S1+2 and he was performed surgery. Because the metastasis of intrahepatic cholangiocarcinoma was demonstrated for lymph node (LN) #3 by intraoperative rapid pathology, only the left upper lobe was resected. Finally, the postoperative pathological diagnosis by thyroid transcription factor-1 (TTF-1) staining was primary lung cancer. Liver lesion was also diagnosed as liver metastases of the lung cancer by TTF-1 staining.