Additionally, the lung mass was histologically similar to the resected urachal carcinoma, with positive expression of CK7, CK20, Villin, and CDX2, and negative for GATA3, TTF1, and NapsinA, supporting the diagnosis of metastatic urachal carcinoma rather than primary lung adenocarcinoma. Here, TTF1 is linked to bladder urachal carcinoma.