[A case of metastatic pulmonary cancer from urachal carcinoma that required differentiation from primary lung adenocarcinoma].

A 58-year-old man was given a diagnosis of urachal carcinoma and underwent a partial cystectomy with enbloc removal of the tumor and radical lymphadenectomy in 2006. In April 2009 he was admitted to our hospital because of hemoptysis and left chest pain. Chest CT showed a 4-cm mass shadow in the left S3 and nodular shadows in the right S1 and left S10. Flexible bronchoscopy demonstrated a tumorous lesion at the orifice of the left B3 bronchus. Although the cytological diagnosis suggested high-grade adenocarcinoma, the tumor was producing mucin and consisted of cells with anisonucleosis, which is not typical of primary lung adenocarcinoma. We then performed immunohistochemical and histological examination of a transbronchial lung biopsy specimen. The histological findings of the specimen were very similar to those of the previously resected urachal carcinoma. In addition, the tumor cells were negative for thyroid transcription factor-1 and surfactant precursor protein B, which are specific to primary lung adenocarcinoma. We therefore diagnosed metastatic pulmonary cancer from urachal carcinoma, which is a rare manifestation in bladder cancer. We report a rare case of metastatic pulmonary cancer from urachal carcinoma that required differentiation from primary lung adenocarcinoma in addition to a discussion of the literature.