adenocarcinoma of urethral diverticulum

Urethral diverticulum adenocarcinoma is a rare occurrence in a urethral diverticulum.

Epidemiology

Urethral diverticulum seen in ~0.6-6% of women. In small series, only 3-6% of resected urethral diverticula show adenocarcinoma .

Clinical features

Urinary frequency, urgency, burning micturition and dysuria are usual presenting symptoms or urethral diverticulum . There is no specific clinical presentation of adenocarcinoma in a diverticulum.

Pathology

Urethral diverticulum carcinomas include transitional cell carcinoma, squamous cell carcinoma and adenocarcinoma. Adenocarcinoma is the most common subtype (60%) .

Radiographic features

Voiding cystourethrogram (VCUG)

Contrast-filled outpouching from urethra with partial filling / contrast retention during voiding. Adenocarcinoma is seen as a filling defect within the diverticulum .

Double balloon urethrography

Double balloon urethrography can be used to forcefully inject contrast into diverticular orifice, although its use is now uncommon, if MRI is available.

Ultrasound

On transabdominal ultrasound, a distended urethral diverticulum is seen posterior to urinary bladder (in females, it is a similar location to prostate). A carcinoma may present as a polypoidal or diffuse mass lesion within.

Transvaginal or endourethral ultrasound may have a higher sensitivity for detection.

CT

CT is not the preferred modality for evaluation of the pelvis. If the urethral diverticulum is large, it may present as a well-defined thick-walled cystic lesion, at the level of pubic symphysis. A carcinoma may present as an enhancing mass within the diverticulum.

CT would theoretically be able to stages a urethral diverticulum adenocarcinoma, in terms of local or regional invasion, better than ultrasound. It can also easily differentiates diverticular calculi from soft tissue in the diverticulum. Differentiation may be difficult on VCUG.

MRI
  • T1: diverticulum is seen as hypointense signal area around the urethra, or sometimes as a homogenous hypointense signal enlarged urethra. A carcinoma as heterogenous enhancing mass with thickened wall of diverticulum.
  • T2: diverticulum is seen as hyperintense signal area around the urethra
Fiberoptic urethroscopy

Diverticulum can be well visualized on urethroscopy, if the orifice is well identified.

Differential diagnosis

  • calculi in diverticulum (may appear as filling-defect in VCUG)
  • vaginal adenocarcinoma
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