Urethral carcinoma can be classified as primary, which is defined as “first carcinoma in the urinary tract that originates from the urethra”, or secondary, which presents as
recurrent carcinoma in the urethra after prior diagnosis and treatment of a carcinoma elsewhere in the urinary tract, more frequently in the bladder.
Primary
The primary urethral carcinoma is an extremely rare tumor that accounts for less than 1% of the total incidence of all malignancies. Incidence of primary urethral carcinoma peaked in the elderly population (>75 years), with an age-standardized rate of 4.3/million in men and 1.5/million in women, compared with almost negligible in younger population aged <55 years (0.2/million).
Risk factors
In men, predisposing factors for primary urethral carcinoma include urethral strictures, chronic irritation after intermittent catheterization, radiation therapy, chronic urethral inflammation or urethritis following sexually transmitted diseases (e.g. condylomata associated with human papilloma virus), and lichen sclerosus. In female, predisposing factors include urethral diverticula and recurrent urinary tract infections.
Histopathology
In men, the three predominant histological types of primary urethral carcinoma are the urothelial carcinoma (54–65%), followed by squamous cell carcinoma (16–22%) and adenocarcinoma (10–16%).
In female, adenocarcinoma is the most frequent histology (38–46.7%) followed by squamous-cell carcinoma (25.4–28%), and urothelial carcinoma (24.9–28%).
Secondary
Urethral carcinoma can co-exist at the time of diagnosis (synchronous) or develop consequently (metachronous) after resection of the first primary urinary tract carcinoma.
In those patients with synchronous tumors, the urethral cancer represents a sign of local spread of the primary lesion into the lower urinary system. In those patients with metachronous tumors, the urethral cancer represents a sign of recurrence of the primary lesion.
Incidence
After radical cystectomy due to invasive bladder cancer, the incidence of urethral tumors is <5%. Risk factors for secondary urethral tumors are urethral malignancy in the prostatic urethra/prostate (in men) and bladder neck (in women).
Histopathology
The predominant histological type of secondary urethral tumors is urothelial carcinoma, which as well developed after a primary urothelial carcinoma.
Symptoms
Urethral carcinoma at initial stage can be asymptomatic, and patients can develop symptoms only when the tumor is locally advanced. Common symptoms include visible haematuria or bloody urethral discharge, that are reported in up to 62% of the cases. Additional symptoms of locally advanced disease include extra-urethral mass (52%), bladder outlet obstruction (48%), pelvic pain (33%), urethrocutaneous fistulae (10%), abscess formation (5%), or dyspareunia.
