A Case Report of an Inverted Papilloma of the Prostatic Urethra and a Synchronous Low-Grade Papillary Carcinoma of the Bladder

doi:10.4236/ojpathology.2012.24025

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Open Journal of Pathology, 2012, 2, 140-142

Published Online October 2012 (http://www.SciRP.org/journal/ojpathology)

http://dx.doi.org/10.4236/ojpathology.2012.24025

A Case Report of an Inverted Papilloma of the Prostatic

Urethra and a Synchronous Low-Grade Papillary

Carcinoma of the Bladder

Han-Seung Yoon1,2, A. Dempster 2

1Department of Pathology, Dunedin School of Medicine, Otago University, Dunedin, New Zealand; 2Southern Community Laborato-

ries, Dunedin, New Zealand.

Email: [email protected]

Received July 18th, 2012; revised August 17th, 2012; accepted August 29th, 2012

ABSTRACT

Inverted urothelial papilloma is a rare benign tumour and represents one of the urothelial lesions with inverted mor-

phology. Accurate diagnosis and differentiation from other inverted lesions is important because its proper clinical

management and expected clinical outcomes are distinctly different. Here we describe a case of a large inverted urothe-

lial papilloma of the prostatic urethra and a synchronous non-invasive low-grade papillary urothelial carcinoma of the

bladder in a 60-year-old man. We focus on the differential diagnosis of inverted urothelial papilloma.

Keywords: Inverted Papilloma; Papillary Urothelial Carcino ma; Prostatic Urethra; Urinary Bladder

1. Introduction

A number of well-recognized urothelial lesions with in-

verted morphology occur in the urinary tract. Among

them inverted papilloma is a rare tumor accounting for

less than 1% of all urothelial neoplasms [1-4]. Its recog-

nition is important because of similarities to inverted

urothelial carcinoma, especially in small biopsy speci-

mens. Here we report a case of a large inverted papilloma

and a concomitant low-grade non-invasive papillary

urothelial carcinoma of the urinary bladder in a 60-year-

old male.

2. Case Report

A 60-year-old male complained o f intermittent hematuria

including occasional episodes of gross hematuria over

the previous 14 months. A urine flow test showed ob-

structive features. Digital rectal examination showed an

approximately 30-gram clinically benign prostate. The

PSA level was within the normal range. Urine cytology

was negative. Cystoscopy showed a tiny papillary lesion

just at the level of the trigone between the two ureteric

orifices. The lesion was biopsied. Its histology showed a

low-grade non-invasive papillary urothelial carcinoma

(Figure 1).

Furthermore there was prolapse of the middle lobe of

the prostate. Prostate chips weighing 4.5 grams were

examined. Histology showed multiple fragments of cel-

lular tissue a few of which had a normal urothelial sur-

face. The majority of tissue fragments contained numer-

ous nests of basaloid epithelial cells with prominent pe-

ripheral palisading (Figures 2 and 3). Areas of non-

keratinizing squamous differentiation were present (Fig-

ure 4). There were also frequent glandular structures or

cystic spaces of varying size lined by flattened urothelial

cells and basaloid epithelial cells containing variable

amounts of homogenous eosinophilic material within the

central lumen (Figure 5). Neither intestinal metaplasia

nor goblet cells were present. Although the tumor showed

Figure 1. Low-grade non-invasive papillary urothelial car-

cinoma containing occasional thin fibrovascular stalks (H &

E 100×).

A Case Report of an Inverted Papilloma of the Prostatic Urethra and a Synchronous

Low-Grade Papillary Carcinoma of the Bladder 141

Figure 2. Numerous nests of basaloid epithelial cell (H & E

100×).

Figure 3. A higher magnified image of Figure 2 showing

nests of basaloid cells with peripheral palisading (H & E

200×).

Figure 4. Some areas show prominent squamous differen-

tiation (H & E 200×).

focal mild epithelial atypia and scattered mitotic figures,

there was no evidence of invasive malignancy. The fea-

tures were those of an inverted urothelial papilloma.

None of the chips contained prostatic acinar glandular

tissue.

Three weeks after the initial d iagnosis, further prostate

chips weighing 32.2 gram were transurethrally resected.

Histological appearances of this material were identical

to those of the first. In add ition th e 2nd sp ecimen sho w ed

focal non-neoplastic areas of cystitis glandularis associ-

ated with a mild chronic inflammatory infiltrate (Figure

6). The tumor was diagnosed as an inverted urothelial

papilloma, trabecular type associated with cystitis glan-

dularis, originating from the prostatic urethra. No recur-

rence of vesical papillary urothelial carcinoma or pro-

static urethral inverted papilloma has b een record ed up to

now.

Figure 5. Frequent areas of glandular differentiation con-

taining eosinophilic secretory materials (H & E 100×).

Figure 6. Focal non-neoplastic areas show features of cysti-

tis glandularis in association with chronic inflammatory

infiltrate (H & E 200×).

A Case Report of an Inverted Papilloma of the Prostatic Urethra and a Synchronous

Low-Grade Papillary Carcinoma of the Bladder

142

3. Discussion

Inverted papilloma of the urinary tract is a rare benign

tumor most commonly diagnosed in older men present-

ing with hematuria or symptoms of lower urinary tract

obstruction [3,4]. It is most frequently identified in the

bladder neck or trigone as a polypoid growth with a

smooth surface. These lesions are usually small (<3 cm)

but can be large. Most are solitary although 1% - 4%

may be multifocal.

Histologically there are two main subtypes of inverted

papillomas; trabecular and glandular [1]. The former is

characterized by widely branched, anastomosing cords of

urothelial cells originating directly from the overlying

transitional epithelium. The latter is characterized by

multiple round to oval islands of proliferating urothelial

cells together with pseudoglandular and true glandular

structures, which are often connected with the surface

urothelium.

Although inverted papilloma is generally regarded to

be a benign neoplasm, sporadic cases of inverted papil-

loma with malignant features have been reported raising

concern that inverted papilloma may be a precursor le-

sion of utorhelial malignancy [5-8]. However most of

these patients had a history of previous or concurrent

urothelial carcinoma. Inverted papilloma is associated

with a low risk of recurrence (5%), in marked contrast to

the high recurrence rates of papillary urothelial carci-

noma [3]. Sung et al. [2] reported only one recurrence

among 75 patients with inverted papilloma (1.3%) during

a mean follow-up of 68 months after treatment. The au-

thors recommend that complete transurethral resection

appears to be adequate surgical therapy for inverted

papilloma [2].

The present case showed an inverted papilloma of the

prostatic urethra and a synchronous low-grade non-inva-

sive papillary urothelial carcinoma of the bladder. Spo-

radic cases with inverted papilloma have been reported to

show metachronous or synchronou s urothelial carcinoma.

Brown and Cohen in a series of 41 cases of inverted

papilloma reported 2 patients (4.9%) had a history of

urothelial carcinoma and one of the 2 (2.4%) was diag-

nosed with concomitant urothelial carcinoma [4]. The

authors recommend ed postoperativ e surveillance because

2 patients developed urothelial carcinoma among 25 pa-

tients during a 9 - 25 months cystoscopic follow-up for

non-recurrent inverted papilloma.

Differential diagnosis of inverted papilloma from other

inverted urothelial lesions rests primarily on morpho-

logical criteria. Recognition of the possibility o f inverted

papilloma in the differential diagnosis remains the best

safeguard against incorrect diagnosis [9]. The differential

diagnosis includes non-neoplastic lesions such as von

Brunn’s nest, florid von Brunn’s nest proliferation, cysti-

tis cystica and cystitis glandularis as well as neoplastic

lesions such as inverted urothelial carcinoma, nested

variant of urothelial carcinoma and verrucous squamous

cell carcinoma.

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