Immunostains showed the cells had patchy positivity for Pax‐8 and GATA‐3, and focal weak positivity for pancytokeratin and p63, while they were negative for TTF‐1, CK7, CK20, CA‐IX, and 34‐beta‐E‐12, compatible with a metastasis from a sarcomatoid neoplasm of renal origin. The gene discussed is TTF1; the disease is neoplasm.