Urethral caruncles are benign, distal urethral lesions that are most commonly found in postmenopausal women. Recently, a case of urethral caruncle has also been described in a male. Urethral caruncles resemble various urethral lesions, including carcinoma. The differential diagnoses of urethral caruncle include urethral diverticulum, urethral prolapse, urethral carcinoma, and periurethral gland abscesses.
Urethral caruncles, which often originate from the posterior lip of the urethra, may be described as fleshy outgrowths of distal urethral mucosa. They are usually small but can grow to 1 or more cm in diameter.
Urethral caruncles are common in elderly postmenopausal women but are rare in premenopausal or perimenopausal women. Urethral prolapse is similar in appearance, but is circumferential while caruncles are focal. Urethral prolapse may occur in prepubescent or postmenopausal females, whereas caruncles are seen almost exclusively in the latter.
Urethral caruncles may develop from several simultaneous processes, as discussed in the Pathophysiology section.
The first step in the development of a urethral caruncle is likely distal urethral prolapse caused by urogenital atrophy due to estrogen deficiency. Chronic irritation, where the urethral mucosa is exposed, contributes to the growth, hemorrhage, and necrosis of the lesion.
Cases of urethral melanoma, tuberculosis,[3, 4] intestinal ectopia, lymphoma,[5, 6] and urethral leiomyoma masquerading as urethral caruncle have been reported; however, reports of these associations are rare. Intraepithelial squamous cell carcinoma arising within a urethral caruncle has been reported in 2 patients. Additionally, urethral caruncles have been reported to occur rarely in the premenopausal patient and may enlarge during pregnancy. Urethral polyps are the pediatric equivalent of urethral caruncles and manifest in a similar fashion.
Most urethral caruncles are asymptomatic and are incidentally noted on pelvic examination; however, some may be painful and others may be associated with dysuria. Many individuals with a urethral caruncle present with bleeding or, more commonly, with the patient noticing blood on undergarments. Urethral caruncles are unlikely to explain voiding or storage symptoms in women. In fact, a comparison of lower urinary tract symptoms and urodynamic factors in incontinent women with and without caruncles found no differences.
On examination, they most often appear clinically as a pink or reddish exophytic lesion at the urethral meatus; in rare cases, they are purple or black secondary to thrombosis. Some caruncular lesions may resemble urethral carcinoma.
Conservative therapy (ie, warm sitz baths, topical estrogen creams, topical anti-inflammatory drugs) is appropriate in most patients. Surgical intervention should be reserved for patients with larger symptomatic lesions, for those in whom conservative therapy fails to elicit a response, and for those with uncertain diagnoses.
The female urethra is a 4- to 5-cm tubular structure. It is normally lined by nonkeratinized stratified squamous epithelium distally and transitional epithelium proximally. Outer layers have a complex network of smooth muscle fibers and vascular structures.
Surgical therapy should be reserved for women with larger symptomatic lesions and for women with uncertain diagnoses.
Obtain a urinalysis to rule out urinary tract infection when pain, discomfort, or dysuria is present or when an operative intervention is planned.
A urethral caruncle is obvious on physical examination, and biopsy is unnecessary in the vast majority of cases.
Cystoscopy can be performed, either in the office or at the time of excision, to rule out more serious pathologies or when the origin of hematuria is uncertain. Cystoscopy is not necessary when the diagnosis is obvious, hematuria is absent, and no intervention is planned.
Microscopically, a urethral caruncle resembles a bed of granulation tissue covered by either squamous or transitional epithelium. Infolding of epithelium may create papillary architecture. Inflammatory infiltration is common (see image below).
This image shows marked vascular engorgement and a polymorphous inflammatory infiltrate in the stroma. Surface epithelium is benign. Courtesy of G.T. ....
A pathology series of 41 patients demonstrated mixed hyperplastic urothelial or squamous lining. The stroma demonstrated fibrosis, edema, and/or inflammation. Immunohistochemistry for immunoglobulin G (IgG) and IgG4 has been shown in a subset of patients, suggesting a possible autoimmune factor in some patients. This finding warrants further study.
Most urethral caruncles can be treated conservatively with warm sitz baths and vaginal estrogen replacement. Topical anti-inflammatory drugs may also be useful. Unfortunately, data on the efficacy of conservative management are lacking in the literature.
Reserve surgical intervention for patients with larger symptomatic lesions and for those with uncertain diagnoses. Induration, failure to respond to conservative therapy, atypical appearance, or growth over time may be indications for excisional biopsy. Tumors are found in approximately 2% of urethral caruncles.
Standard vaginal preparation and preoperative antibiotics are recommended.
Excision is usually an outpatient operation and involves the following steps:
A Foley catheter may be left in place for 1-2 days to allow for appropriate healing of the urethral mucosa.
If the lesion is benign, no special follow-up is required.
If the epithelium is not everted adequately with the stay-stitch, meatal retraction and stenosis may occur.
The prognosis is excellent if pathology confirms urethral caruncle as the diagnosis.
Urethral caruncle management is straightforward. As the etiology of these lesions is better elucidated, improvements in medical therapies may obviate surgery.