Urethral Metastasis from Rectal Adenocarcinoma: A Case Report and Review of the Literature

Case A 73-year-old man with Dukes' C adenocarcinoma of the rectum, pT3N2bM0, stage IIIB, presented with voiding difficulties including poor stream and terminal dribbling for one month. The patient was under careful surveillance and had no postoperative recurrence. Physical examination revealed a palpable irregular nodular lesion (0.5 × 0.5 cm2) at the penile-scrotal junction. He underwent urethroscopy, which showed a cauliflower lesion in the pendulous urethra. Transurethral resection was performed and histopathologic and immunochemical staining demonstrated a metastatic moderately differentiated urethral adenocarcinoma from the colorectal primary. Outcome His voiding disorder improved significantly post-operation and he commenced second-line chemotherapy combined with regional radiotherapy. Follow-up urethrocystoscopy and abdominal computed tomography demonstrated no recurrence or metastatic disease. His tumor marker remained within the normal range for 12 months. Conclusion Urethral metastasis from primary colon cancer is extremely rare. This disease, with its various atypical presentations, presents a diagnostic challenge to the clinician. In patients with recurrent or persistent lower urinary tract symptoms, further urologic workup including thorough history taking, physical examination, and imaging surveys is warranted.