Urachal carcinoma grows invasively and metastasizes locally in most cases. We have experienced a rare case of urachal carcinoma causing solitary bone metastasis without local recurrence after radical operation.
A 77-year-old man with previous histories of pulmonary emphysema and arrhythmia underwent total cystectomy with en bloc removal of the tumor and radical lymphadenectomy under the diagnosis of urachal carcinoma in April 2004. The histopathological diagnosis was well differentiated adenocarcinoma (pT3b, n0, m0). He had been followed after 2 courses of adjuvant chemotherapy (CDDP + 5-FU). In February 2008 he was given close examinations because right chest pain developed, and an image study showed a 3-cm mass shadow in the right 7^th rib without other abnormal lesions. Although tumor markers were in normal limits, we suspected primary bone tumor or bone metastasis from urachal carcinoma, which is a rare manifestation in bladder carcinoma. In March 2008, the patient was re-operated on for the solitary bone tumor. The tumor was 3.0 × 3.0 cm in size. The histological findings of the specimen were extremely similar to those of the previously resected urachal carcinoma. He remains free from the disease 5 years after the second operation. Although bone metastasis of urachal carcinoma is rare, periodic observation for probable bone metastasis might be required.