Solitary fibrous tumor mimicking prolapsed ureteral polyp.

Solitary fibrous tumor of the ureter is extremely rare. We describe a case where the polyp was prolapsing into the bladder mimicking a bladder tumor.

INTRODUCTION

Primary neoplasms of the ureter are very rare, with a prevalence of < 1% of all genitourinary tumors. Benign tumors include fibroepithelial polyp, leiomyomas, neurofibromas, hemangiomas and endometriosis.[12] We present images of a solitary fibrous tumor of the ureter that prolapsed into the bladder and appeared as a primary bladder tumor.

CASE REPORT

A 60-year-old female presented with a 5-month history of progressive worsening of the flow of urine. She had no other lower urinary tract symptoms, no hematuria or abdominal pain. She was hypertensive and hypothyroid, on treatment and had undergone an abdominal hysterectomy 20 years back. Abdominopelvic ultrasound revealed a hypoechoic mass measuring 12 mm × 9 mm at the base of the bladder with normal upper urinary tract. An abdominal computed tomography (CT) scan confirmed the same mass with no hydronephrosis [Figure 1].

Figure 1

Computed tomography scan showing the mass in the bladder base

Cystourethroscopy revealed a mass protruding through the right ureteric orifice and resting on the base of the bladder [Figure 2]. Ureteroscopy revealed the stalk of the pedunculated tumor at about 1 cm proximal to the ureteric orifice [Figure 2]. The tumor was resected using a holmium laser with a 350 μm fiber with settings of 8 Hz and 1.0 Joules (8 Watts). Histology of the resected tumor had normal transitional epithelial lining. Subepithelial tissue revealed a lesion composed of bland spindle cells arranged randomly with the intervening stroma showing collagenization [Figure 3]. Tumor cells were CD34 positive and negative for smooth muscle actin (SMA) and desmin, thereby favoring a diagnosis of solitary fibrous tumor. In view of no significant inflammation in the neoplastic process, possibility of inflammatory fibrous polyp was excluded. At 3 months of follow-up, the patient was asymptomatic and CT urogram showed normal functioning right kidney.

Figure 2

Cystoscopic finding (left) and finding at ureteroscopy showing the stalk of the polyp (right)

Figure 3

Photomicrograph showing bland spindle cell proliferation in the subepithelium. The overlying transitional epithelial lining is unremarkable (original magnification, hematoxylin and eosin, 20x)

DISCUSSION

Neoplasms of the ureter are very rare, and they can either be of epithelial or mesenchymal origin. Epithelial tumors are mostly malignant while the mesenchymal tumors are benign.[2] In this case, the histology turned out to be solitary fibrous tumor, which is a very rare tumor. Such tumors are mostly found in the pleura. Other reported sites aremeninges, retroperitonium, breast, liver and intestines.[3] Although cases affecting the kidney, bladder and seminal vesicles have been reported, only two were found in the literature affecting the ureter.[4]

Ureteral polyps commonly occur in the proximal ureter and are usually solitary and can extend to the renal pelvis causing hydronephrosis.[23] When they occur in the distal ureter, they may extend or prolapse into the urinary bladder, thereby causing diagnostic dilemma such as in the case of our patient. There are no specific guidelines for the treatment of ureteral polyps.[1] The goal is to have complete excision of the stalk.

In conclusion, solitary fibrous tumor of the ureter is very rare and should be considered in the differential diagnosis of ureteral polyp. Holmium laser is an easy and effective means of ureteral polyp excision.