In May 2007, a 45 year old man underwent an open sigmoid colectomy, loop ileostomy and partial resection of the posterior bladder wall for a pT4 adenocarcinoma of the sigmoid colon. He initially presented with recurrent, treatment-resistant urinary tract infections. Diagnostic flexible cystoscopy revealed an inflammatory mass at the posterior bladder wall. No obvious fistula was seen at that time. Colonoscopy revealed a large suspicious looking sigmoid mass. Histology from both the diagnostic trans-urethral resection and colonoscopic biopsy demonstrated adenocarcinoma, consistent with a bowel primary. A staging CT of his thorax, abdomen and pelvis demonstrated a complex pelvic mass, suspicious for malignancy at the sigmoid colon / bladder region. There was no evidence of distal metastatic disease. A sigmoid colectomy with en bloc resection of a portion of bladder was performed. A primary end-to-end colorectal anastomosis was constructed with proximal defunctioning ileostomy. Post operative histology revealed a 7cm moderately differentiated colonic adenocarcioma with transmural bladder invasion to the bladder mucosa. Thirteen lymph nodes retrieved were free of tumour. Colonic, soft tissue and bladder mucosal margins were clear. There were no features of microsatellite instability. Post operatively he received adjuvant chemotherapy using the FOLFOX regimen (Folinic acid, Fluorouracil (5-FU), Oxaliplatin). Following completion of this treatment he underwent reversal of his loop ileostomy. Follow up with the colorectal, urology and oncology teams was completed according to institutional guidelines. He had an annual colonoscopy along with bi-annual CT of thorax, abdomen and pelvis and measurement of CEA and CA-125 tumour markers. All of the above investigations were within normal limits with no evidence of disease recurrence or metastasis when last seen routinely in December 2009.
However the patient presented emergently four months later complaining of gross painless haematuria. Attempted cystoscopy revealed an abnormal, exophytic lesion in his proximal penile urethra (Fig. 1).
Figure 1. Urethroscopic view of metastasis at the bulbar urethra
This lesion obscured the urethral lumen but the flexible cystoscope was able to pass into the bladder at the 10 0’ clock position. Completion cystoscopy revealed no additional bladder neoplasm. Biopsies of this urethral lesion confirmed adenocarcinoma with villo-glandular morphology, consistent with colorectal metastasis. A CT scan revealed liver metastasis, which correlated with positive PET scan assessment. His PET scan also showed a ‘hot spot’ at the junction of his penile and bulbar urethra (Fig. 2).
Figure 2a. Coronal PET CT slices demonstrating ‘hotspot’ at the bulbar urethra
Figure 2b. Axial PET CT slices demonstrating ‘hotspot’ at the bulbar urethra
Following discussion at our institution’s multi-disciplinary team meeting the management of this patient’s urethral metastasis involved local urethroscopic excision followed by local radiotherapy. The patient was carefully counseled regarding the potential complications (urethral stricturing, recurrence) and limitations of this course of treatment. In view of the fact that he had hepatic metastases, formal urethral excision with reconstruction was deemed not suitable. He is currently undergoing chemotherapy for distal disease control. He remains well and is voiding per urethra with a good subjective flow rate.
Urethral metastasis from distal primary sites is rare, accounting for less than 0.02% of all urological malignancies. Metastasis from renal cell carcinoma , melanoma , prostate adenocarcinoma  and lung  have all been described. Metastasis from a colorectal primary is even rarer. To the best of our knowledge there have been only ten previous cases reported in the medical literature [4-11].
Various hypotheses on the mechanism of metastasis have been proposed, though there remains controversy as to which is most likely. The mode of spread could potentially arise from direct infiltration, retrograde lymphatic or a retrograde haematogenous route. Some authors have suggested that recurrence may occur secondary to changes in pelvic lymphatic flow arising from operative intervention . This theory is supported by the finding that female patients who undergo a cystectomy for bladder cancer are more likely to develop vaginal metatasis when there are positive pelvic nodes . However another possible explanation is that in these cases, vaginal metastasis occurs as a result of having more locally advanced disease and may not be due to disruption of normal lymphatic drainage. The most likely mechanism of spread in this case is the hypothesis proposed by Yoshimura et al . That is, that urethral metastasis arises from direct seeding of colonic cancer cells via the urine.
The presentation of urethral metastasis, which predominantly occurs in the bulbar urethra (in males) is quite varied. In male patients, mixed lower urinary tract symptoms (LUTS) and acute urinary retention are the most commonly reported symptoms. In only two other reported cases was frank painless haematuria the predominant symptom. Occasionally a penile or perineal mass is palpable which suggests a more locally advanced stage. In female patients voiding difficulty, dysuria and bloody discharge appear to predominate.
Given the rare nature of urethral metastasis arising from a colorectal primary various authors have suggested that routine urethroscopy +/- cytological brushings as part of the follow up care of the patient is not warranted [4,10]. All patients with a history of locally advanced colonic / rectal adenocarcinoma presenting with new-onset LUTS, haematuria or acute urinary retention should have a full work-up of both their upper and lower urinary tracts. In addition we suggest that even in the absence of urinary symptoms all patients should have bi-annual urinary dipstick to check for microscopic haematuria. Those with microscopic haematuria may then undergo further invasive evaluation. Annual urine cytology could also be sent for laboratory analysis although its diagnostic yield may be limited.
Management of urethral metastasis arising from a gastrointestinal primary should be undertaken via a multi-disciplinary approach. In those with a solitary urethral lesion, local surgical excision is the treatment modality of choice. Urethral reconstruction or urinary diversion may be undertaken at the time of excision or at a later stage. The timing of a secondary procedure may depend on the extent of the lesion, the extent of urethral tissue excised and available expertise to reconstruct the urethra. Although urethral metastasis usually infers a poor prognosis in most cases, an excellent long term survival of seven years post urethrectomy has been previously described . As our patient had extensive distal metastasis (liver) needing additional chemotherapeutic intervention the consensus following multi-disiplinary review was that formal urethral excision and reconstruction was not appropriate. We elected to treat his urethral lesion with local urethroscopic excision followed by radiotherapy. While there is a paucity of data in the medical literature relating to survival advantage offered by this course of treatment, it can provide symptomatic relief of lower urinary tract symptoms. This stopped his haematuria and he is currently voiding normally. He remains well six months post diagnosis of his urethral metastasis.
Urethral metastasis arising from a colorectal primary adenocarcinoma is rare. Treatment must be tailored according to disease stage. The addition of routine urinary dipstick analysis for the presence of microscopic haematuria as part of the follow up protocol for patients with bladder involvement from a colorectal primary may facilitate earlier detection of local recurrence and improve outcomes. This requires evaluation in larger cohorts.
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Date added to bjui.org: 12/07/2011