Abstract
Thyroid transcription factor 1 (TTF-1) is primarily expressed in lung and thyroid cancers, but it has also been observed in other cancers. A 60-year-old woman presented with worsening dyspnea, pleural effusion, lung metastases, a right ovarian tumor, and para-aortic intra-abdominal lymph node metastasis. Biopsies from the pleural dissemination revealed TTF-1-positive adenocarcinomas. To confirm the presence of the primary organ, biopsies were performed on a para-aortic intra-abdominal lymph node that ascended from the ovaries. An adenocarcinoma positive for TTF-1 was identified, thus confirming the diagnosis of ovarian cancer. Our findings revealed that TTF-1 positivity does not always signify a lung cancer origin.