Carcinoma Arising in a Urinary Bladder Diverticulum : Images in Radiology

Primary neoplasms of the urinary bladder diverticula are rare and present with special problems in diagnosis and treatment. All bladder diverticulae are potential sources of hidden neoplasms as they have a late presentation and often diagnosis is delayed. Hence a thorough evaluation of all bladder diverticulae to rule out any underlying malignancy is essential.

Introduction

Carcinomas arising within urinary bladder diverticula have a poor prognosis as compared to neoplasms arising within the bladder lumen due to early transmural infiltration. Imaging plays an important role in the diagnosis and the staging of this disease.1 We describe imaging findings in a 54 year old man who presented with painless haematuria.

Case Report

A 54 year old farmer presented with intermittent painless haematuria since 15 days. There was no past history of renal calculus or urinary stone disease. There was no history of addiction. Ultrasonography (USG) of abdomen and pelvis was performed in the emergency, which revealed a urinary bladder diverticulum with fine internal echoes in the bladder. There was left sided moderate hydronephrosis and hydroureter. Intravenous urogram was performed, which revealed compromised function of the left kidney with moderate to gross hydronephrosis on the left side. A urinary bladder diverticulum was confirmed which was arising from the left posterolateral wall. There was no calculus noted within the diverticulum or the entire urinary tract. The right kidney and ureter were unremarkable. Cystoscopy was performed which revealed a narrow neck diverticulum near the left ureteric orifice with a thickened abnormal mucosa around the orifice of the diverticulum extending into the diverticulum. Subsequently a biopsy was done which showed features suggestive of transitional cell carcinoma. Contrast enhanced CT scan of the abdomen and pelvis was done to evaluate the extent of the lesion and perivesical spread. CT scan showed a 2 cm outpouching of the bladder wall in the left posterolateral region. Left hydroureter was also noted. The medial wall of the diverticulum was thickened and irregular with abnormal enhancement, extending into the bladder. There was no perivesical spread of the tumour. Patient was taken up for surgery and a diverticulectomy with partial cystectomy was performed.


	Fig. 1 : Contrast enhanced CT scan of the pelvis at the level of urinary bladder shows a wide neck diverticulum arising from the left posterolateral wall. There is diffuse thickening of the medial wall of the diverticulum extending into the bladder. Note the dilated left lower ureter.

Discussion

Urinary bladder diverticula are outpouchings of the urothelium through defects in the muscular walls, which usually result from lower urinary tract obstruction. They empty poorly due to lack of muscle fibres in their walls, stenotic orifice or their large size. This leads to a variety of complications which include persistent and recurrent urinary tract infection, ureteral obstruction and the development of a carcinoma within the diverticulum.2 6% of the bladder diverticula are known to be malignant.² Urinary stasis and chronic inflammation leads to the development of dysplasia, leukoplakia and squamous metaplasia in approximately 80% of all diverticuli. Urinary stasis also enhances urothelial susceptibility to urinary chemical carcinogens.² Stasis of urine within poorly contractile urinary bladder diverticulum is the cause of diverticular carcinoma.³ When a bladder tumour and a diverticulum coexist, the tumour is most often found within the diverticulum.³ Histopathologically, transitional cell carcinoma is the most common tumour to arise in a bladder diverticulum. Few cases of an adenocarcinoma,⁴ sarcoma⁵ and verrucous carcinoma⁶ arising in a bladder diverticulum have been reported.

The thin walls of the diverticulum with relative lack of muscular elements facilitates early, complete peneteration by neoplasms found within them. This, together with a delay in diagnosis accounts for the relatively poor survival with this unusual combination of the disease. Therefore all bladder diverticuli should be regarded as potential sources of hidden neoplasm.²

Intravenous urography and cystourethroscopy have been the mainstage in urologic evaluation of such patients, but CT and USG are increasingly used and are better modalities in preoperative assessment and diagnosis of bladder diverticular carcinomas.² Transabdominal US has its limitations in evaluating the bladder neck and dome but is excellent is assessment of diverticuli arising from the posterior or the lateral walls, which are the most common sites of bladder diverticuli.² USG can identify the presence, location and extent of the tumour.²

Computed tomography is one of the best modalities for staging of bladder tumours. Preoperative CT evaluation helps delineate the depth and the degree of extension of the primary lesion.² On CT, urinary bladder diverticular carcinomas appear as a diffuse or focal thickening of the wall of diverticulum with or without extension into the perivesical region. The lesions typically show inhomogenous enhancement following contrast administration. Evaluation of the remaining urinary tract can also be done in the same sitting.

Cystoscopy is used for confirmation of the disease and as a guide for tissue sampling. However, frequently cystoscopy may fail to disclose a tumour in the diverticulum due to a tight orifice or a small lesion at the base of the diverticulum.²

The interior of all bladder diverticuli should be inspected with a combination of cystoscopy, panendoscopy and radiography. These studies coupled with increasing routine use of cytological examination, should avoid undue delay in the diagnosis of this disease.³

When a tumour is found within a vesical diverticulum, treatment in most cases consists of a wide excision of the diverticulum together with a segment of the bladder surrounding the neck of the diverticulum.³ The classic therapy includes a segmental cystectomy with diverticulectomy. Those with extensive perivesical involvement should receive adjuvant chemotherapy. The role of preoperative radiotherapy in such patients is controversial.²

References

1. Dondalski M, White EM, Ghahremani GG, Patel SK. Carcinoma arising in urinary bladder diverticula: imaging findings in six patients. AJR 1993; 161 (4) : 817-20.

2. Lowe CF, Goldman SM, Oesterling JE. Computerized tomography in evaluation of transitional cell carcinoma in bladder diverticula. Urology 1989; 34 (6) : 390-5.

3. Montague DK, Boltuch RL. Primary neoplasms of the vesical diverticula : Report of 10 cases. J Urol 1976; 116 : 41-2.

4. Lam KY, Ma L, Nicholls J. Adenocarcinoma arising in the diverticulum of the urinary bladder. Pathology 1992; 24 (1) : 40-2.

5. Kim MY, Jeon YS, Suh CH, et al. Sarcomatoid carcinoma arising from the diverticulum of the urinary bladder dome. A difficult diagnosis with imaging. AJR 1999; 172 (5) : 1454-55.

6. Chiang PH, Chou YH, Chiang CP, et al. Verrucous carcinoma of a bladder diverticulum. Br J Urol 1991; 68 (3) : 320-1.