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cal treatment. Key words: Fibroepithelial polyps—Ureter—Transi- tional cell carcinoma—Hematuria—Mass. Fibroepithelial polyps of the urinary tract are quite ...
Abdom Imaging 27:217–221 (2002) DOI: 10.1007/s00261-001-0066-z

Abdominal Imaging © Springer-Verlag New York Inc. 2002

Fibroepithelial polyps of the urinary tract T. R. Williams,1 B. J. Wagner,2 W. R. Corse,3 J. C. Vestevich1 1

Naval Medical Center San Diego, Department of Radiology, 34800 Bob Wilson Drive, San Diego, CA 92134-5000, USA West Reading Radiology Associates, 301 South 7th Avenue, Suite 135, West Reading, PA 19611, USA 3 Parlee & Tatum, Doylestown Hospital, 595 West State, Doylestown, PA 18901, USA 2

Received: 16 February 2001/Accepted: 18 April 2001

Abstract Background: Fibroepithelial polyps of the urothelium are rare but frequently mistaken for transitional cell carcinoma. To better define the demographics, urothelial distribution, and typical gross anatomic and radiologic appearances, we reviewed 41 pathologically proven cases. Methods: We reviewed 41 cases of fibroepithelial polyps from the archives of the Armed Forces of Pathology. Data were collected from radiographic studies, gross anatomic pathology, and pathology and radiology reports and categorized by age, sex, clinical presentation, lesion size, location, and morphology. Results: The mean patient age was 21 years, and 58% were male. Most presented with hematuria and/or flank pain (68%). Most polyps were located in the upper ureter or renal pelvis (87%). Posterior urethral and bladder polyps were present in children. Most polyps were single or bilobed (73%) and 1– 6 cm. Conclusion: Because most urtothelial tumors are malignant epithelial tumors, fibroepithelial polyps are commonly mistaken for transitional cell carcinomas. However, because fibroepithelial polyps and malignant urothelial tumors typically present in different patient populations, different locations in the urinary tract, and appear different radiographically, distinguishing features between these entities is helpful in determining the differential diagnosis of a urothelial mass. In the appropriate clinical setting, fibroepithelial polyps should be considered in the differential diagnosis, which will affect surgical treatment. Key words: Fibroepithelial polyps—Ureter—Transitional cell carcinoma—Hematuria—Mass.

medical literature [1– 4]. The radiologic literature concerning this benign mesodermal tumor consists primarily of case reports. To better define the gross anatomic and radiologic features of this lesion, we reviewed 41 pathologically proven cases. Fibroepithelial polyps typically present in young patients as a smooth, mobile, pedunculated mass in the upper urinary tract. The morphologic and clinical features should allow one to suggest the diagnosis of fibroepithelial polyp rather than the more common urothelial malignancy; that consideration can determine treatment and the surgical approach.

Material and methods We retrospectively reviewed 41 pathologically proven cases from the archives of the Department of Radiology of the Armed Forces Institute of Pathology. Case material included radiologic and pathologic reports, gross photographs, and radiologic images. Every case included an intravenous urogram or similar contrast study such as a retrograde ureteral study or cystogram. Four cases included computed tomographic images, and four separate cases included ultrasound imaging. Each case was categorized by age, sex, and clinical presentation and by polyp size, location, and radiographic and gross appearances. These data were tabulated from radiologic and pathologic reports, imaging features, and anatomic gross photographs (Table 1).

Results Fibroepithelial polyps of the urinary tract are quite rare. Approximately 161 cases have been documented in the Correspondence to: T. R. Williams

The age range of the 41 patients was newborn to 51 years, with a mean age of 21 years. Twenty-four (58%) were male. Twenty-eight (68%) presented with flank pain, hematuria, or both. Eight (19%) presented with hematuria, 14 (34%) with flank pain, and six (15%) with flank pain

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Table 1. Case characteristics Case

Age (years)

Sex

Location

Size (cm)

Gross findings

Margin

Presentation

1 2 3 4 5 6 7 8 9 10 11 12

40 12 NB 16 15 7 12 15 17 38 4 3.5

M M F F F M M M F M M M

Left middle ureter Left middle ureter Bladder Right distal ureter Bilateral proximal ureters Bilateral proximal ureters Right proximal ureter Left proximal ureter Left middle ureter Right pelvis Urethra Right proximal ureter

3.5 4.5 3.8 3.0 2.5 1.0 3.0 4.0 4.1

Bilobed Polyp Polyp Bilobed Filiform Bilobed Polyp, bilobed mass Polyp, bilobed Polyp, bilobed Mass Polyp Polyp

Smooth Smooth Smooth Smooth Smooth Smooth Mildly irregular Mildly irregular Smooth Mildly irregular Smooth Smooth

Hematuria, flank pain Hematuria, flank pain Urethral meatus mass Hematuria Incidential Bilateral flank pain Flank pain Hematuria Flank pain

13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

40 19 35 49 44 14 51 35 2 4 40 27 18 20 35 2 14 4 46 14 7 39 21 27 30 14 31 21 5

M M F F F M M F F M F M M M F F F M F F M M M F F M M M M

Right proximal ureter Right UPJ Left pelvis Right pelvis Left proximal ureter Left middle ureter Left distal ureter Right pelvis Bladder Bladder Left proximal ureter Left proximal ureter Left proximal ureter Right middle ureter Left pelvis Left pelvis Left middle ureter Right UPJ Right UPJ Left proximal ureter Left middle ureter Right proximal ureter Left proximal ureter Right middle ureter Left proximal ureter Left ureter Left proximal ureter Left middle ureter Urethra

2.0 1.8 8.0 5.0 2.5 3.0 6.0 3.0 3.7 1.5 5.0 2.0 1.5 2.5 2.5

Bilobed, polyp Polyp Filiform Mass Polyp Polyp Polyp Mass Polyp Polyp Bilobed, polyp Bilobed, polyp Polyp Filiform Mass Mass Multilobular Polyp Polyp Polyp Polyp 3 polyps Polyp Polyp Irregular Polyp Filiform good Lobulated polyp Mobile polyp

Smooth Smooth Smooth Smooth Smooth Smooth Smooth Smooth Smooth Smooth Smooth Smooth Smooth Mildly irregular Smooth Smooth Smooth Smooth Mildly irregular Mildly irregular Mildly irregular Mildly irregular Irregular Smooth Irregular Smooth Mildly irregular Mildly irregular Smooth

2.0 2.5

2.5 3.0 2.0 6.0 1.0 1.0 2.0 3.0 3.0 2.0 2.5 2.0

Hematuria Abdominal mass, hydronephrosis Hematuria Flank pain Flank pain Hematuria Flank pain Hematuria Flank pain Hematuria Labial Dysuria Recurrent UTI Hematuria UTI Hematuria Hematuria, flank pain

Flank pain Flank pain Pain, hematuria Pain Pain Flank pain Hematuria Flank pain Flank pain

NB, newborn; UPJ, ureteropelvic junction; UTI, urinary tract infection

and hematuria. Two presented with dysuria and recurrent urinary tract infections. Thirty cases (73%) involved the ureter (Fig. 1), with 14% in the renal pelvis (Fig. 2) and 12% in the bladder or urethra. Of the cases involving only the ureters, 63% involved the ureteropelvic junction (UPJ) or upper ureter. Two cases of bilateral ureteral involvement were seen (Fig. 3). The five patients with bladder or urethra involvement had a mean age of 3 years. Most cases (73%) presented as a single or bilobed polyp; the others presented as multiple polyps (7%) or filiform (9%) morphology. These polyps were 1– 6 cm, with a mean size of 3 cm. Radiographically, the polyps had a

variable appearance, with most presenting a mobile, smoothly marginated filling defect in the upper ureter or near the UPJ. The filling defect typically was tubular or bilobed when involving the ureter and dilated the ureter around the polyp, but not proximally. In contrast, the much less common polyps in the renal pelvis were typically multiple or frondlike (Fig. 4). One pediatric case involving the lower urinary tract showed a mobile, smooth, tubular filling defect arising from the posterior urethra, which prolapsed into the bladder during the filling phase of a voiding cystourethrogram, only to partly flip back into the urethra during voiding (Fig. 5).

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Fig. 1. A A single ureteral polypoid filling defect on intravenous urogram with ureteral stent. B Typical computed tomographic appearance of ureteral polyp after contrast enhancement, causing ureteral dilatation without obstruction. C Typical gross view of a single polyp.

Fig. 2. Typical frondlike appearance of a fibroepithelial polyp in the left renal pelvis, causing expansion of the renal pelvis on retrograde examination.

Fig. 3. Bilateral fibroepithelial polyps in the right renal pelvis, proximal ureter, and left UPJ, causing bilateral hydronephrosis.

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Fig. 4. (A) Retrograde pyelogram and (B) gross specimen show multiple polyps at the UPJ.

Discussion Fibroepithelial polyps are rare; however, they are the most common benign mesodermal tumors of the urinary tract. Other rare urinary tract tumors, which are even less common than fibroepithelial polyps, are leiomyomas, lymphangiomas, and neurofibromas [1–3]. Fibroepithelial polyps are mesodermal tumors and composed of a fibrous core covered by normal urothelium [1–5]. They most often are smoothly marginated and cylindrical, sessile, or even frondlike. The etiology of these tumors is not known; congenital, irritative, infectious, obstructive, and traumatic causes have been proposed [4]. Patients are typically young adults who present with gross painless hematuria and/or intermittent or recurrent flank pain. The proposed mechanism for the latter presentation is torsion of the polyp, resulting in painful ischemia or infarction. [4, 6]. Fibroepithelial polyps usually present radiographically as a solitary nonobstructing filling defect near the UPJ on intravenous urography; because they are radiologically indistinguishable from their malignant epithelial counterparts, they are surgically removed for confirmation of the diagnosis and symptomatic relief [7, 8]. Based on current literature, fibroepithelial polyps can occur in newborns and adults older than 70 years but

commonly present in adults in the third through the fifth decades, with a male-to-female ratio of 3 to 2 [2, 6]. Most patients present with flank pain and/or hematuria. Most fibroepithelial polyps occur in the ureter, 15% in the renal pelvis, and a small number in the posterior urethra or bladder. Approximately 62% of ureteral fibroepithelial polyps occur at the UPJ or upper ureter [2, 3, 6]. There is a reported left-sided predominance of about 70% among lesions occurring in the ureters. Fibroepithelial polyps in the lower part of the urinary tract occur most commonly in the posterior urethra and more often in children than adults [6, 9]. Most polyps are smaller than 5 cm, with the largest reported case being a bilobed polyp measuring 14 cm [4]. Cystic transformation of a fibroepithelial polyp and implantation on a ureterocele have been reported [3, 9]. One case of intermittent bilateral hydronephrosis also has been documented [10]. Because of the overlap in clinical presentation and radiologic findings, it becomes a diagnostic challenge to differentiate fibroepithelial polyps from blood clots, radiolucent calculi, or neoplasm. Additional imaging can include noncontrast computed tomography to evaluate for calculi and urine cytology to evaluate for malignancy. Unfortunately, because these polyps are covered with urothelium, urine cytology is of limited use in distin-

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There are useful distinguishing features between epithelial malignancies such as TCC and fibroepithelial polyps: age at presentation, configuration, and location. Fibroepithelial polyps present in a younger patient population as a smooth, often mobile, polypoid mass, in the upper ureter. TCC usually presents in the bladder or lower ureter of an older patient, as a fixed, irregular filling defect [4, 6]. Previous management of fibroepithelial polyps included simple excision and reanastamosis; with the new small-caliber ureteroscopes, current practice is to endoscopically biopsy and resect those ureteral tumors. Ureteroscopy is a widely available, less invasive, and less expensive alternative compared with an open procedure [7–10]. In addition, if the polyps are removed ureterscopically, close follow-up is recommended because of possible recurrence [2]. Therefore, appropriate consideration of fibroepithelial polyps in the differential diagnosis of a urothelial mass is important in the surgical management, potentially preventing unnecessary and costly surgery. In summary, fibroepithelial polyps of the urinary tract are rare. However, because of the unique demographics and distribution relative to urinary tract malignancies, fibroepithelial polyps should be considered in the differential diagnosis in the appropriate clinical setting, which can affect treatment and surgical management. References

Fig. 5. (A) Ultrasound and (B) cystographic images show a tubular filling defect within the bladder lumen.

guishing benign fibroepithelial polyps from malignancy. In addition, because most ureteral epithelial tumors are malignant, establishing the correct preoperative radiologic diagnosis of the very rare fibroepithelial polyp is unlikely and difficult. These benign tumors are commonly mistaken for transitional cell carcinoma (TCC), frequently resulting in more extensive surgery than would otherwise be required for diagnosis and treatment [3, 8]. In one series, 37% of cases were treated with unnecessary nephroureterectomy [3, 11].

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