Immunohistochemistry showed the tumor cells were positive for cytokeratin 7 (CK7), CEA, CK (AE1/AE3, CAM5.2), and thyroid transcription factor-1 (TTF-1) and negative for CK20, estrogen receptor, progesterone receptor, CD5, CD10, neuron-specific enolase, P40, PAX8, GATA3, PSA, CDX2, and NapsinA (Fig. 3 a, b, c). The gene discussed is KRT20; the disease is neoplasm.