Urethral metastasis from a sigmoid colon carcinoma: a quite rare case report, immunohistochemical analysis and review of the literature

Backbround: Urethral metastatic adenocarcinoma is extremely rare. Moreover, only 9 previous cases with metastases from colorectal cancer have been reported to date, and not much information on urethral metastases from colorectum is available so far. Case presentation: We report our experience in the diagnosis and the management of the case with urethral metastasis from a sigmoid colon cancer. A 68-year-old man, who underwent laparoscopic sigmoidectomy for sigmoid colon carcinoma four years ago, presented gross hematuria with pain. Urethroscopy identified a papillo-nodular tumor 7mm in diameter in the bulbar urethra. CT-scan imaging revealed the small mass of bulbous portion of urethra and solitary lung metastasis. Histological examination of the tumor obtained by transurethral resection showed moderately differentiated adenocarcinoma, which was diagnosed as a metastasis of a sigmoid colon carcinoma pathologically by morphological examination. Immunohistochemical analysis of the urethral tumor revealed the positive for cytokertin 20 and CDX2, whereas negative for cytokertin 7. These features were consistent with metastatic adenocarcinoma of the sigmoid colon cancer. As the management of this case with