Markers such as Cytokeratin 7 and 20 are typically used to identify most primary and metastatic adenocarcinomas, while TTF-1 is a tissue-specific transcription factor mainly expressed in thyroid cancer, lung cancer, and high-grade neuroendocrine carcinomas, with minimal expression in extrapulmonary tumors. Here, KRT7 is linked to thyroid gland carcinoma.