For citation purposes: Zibadi S, Sexton WJ, Bui MM, Dhillon J. A large polypoid mass of the bladder: A diagnostic dilemma. OA Case Reports 2014 Jan 18;3(1):2.

Case report

 
Pathology

A large polypoid mass of the bladder: A diagnostic dilemma

S Zibadi1, WJ Sexton2, MM Bui1,3, J Dhillon1,3*
 

Authors affiliations

(1) Department of Cell Biology and Pathology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA

(2) Department of Genitourinary Oncology, Moffitt Cancer Center, Tampa, FL 33612, USA

(3) Department of Anatomic Pathology, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL 33612, USA

* Corresponding author Email:jasreman.dhillon@moffitt.org

Abstract

Introduction

Both neoplastic and non-neoplastic bladder lesions can present as large polypoid masses. Hence, diagnostic biopsy of these lesions becomes imperative to provide valuable information for appropriate therapy. Lesions such as inflammatory myofibroblastic tumour, post-operative spindle cell nodule, sarcomatoid urothelial carcinoma and primary bladder sarcomas may present as polypoid masses. Based on the histological findings, all of these entities may show exuberant spindle cell proliferation. Although, overall histological features in association with immunohistochemical stains may help pathologists to make the correct diagnosis, there are certain pitfalls that warrant caution. We herein present a case that exemplifies this problematic area and highlights the salient histopathologic features and ancillary studies to facilitate the correct diagnosis.

Case Report

We herein report a case of a 71-year-old male who presented with hematuria and on cystoscopy was found to have a large polypoid mass. Histopathologic examination showed a spindle cell lesion.

Conclusion

It is important to carefully examine the spindle cell lesions of the bladder as the differential diagnosis is broad and can range from malignant to benign entities. It is necessary to distinguish these due to therapeutic and prognostic implications.

Introduction

Bladder lesions may present as focal or diffuse mural thickening, intraluminal papillary, sessile and ulcerated or polypoid masses. Primary bladder neoplasms such as urothelial carcinomas, sarcomatoid carcinomas, sarcomas, solitary fibrous tumours and neuroendocrine tumours can present as large polypoid masses[1,2,3]. Non-neoplastic conditions such as inflammatory myofibroblastic tumour (IMT), post-operative spindle cell nodule (PSCN), hamartoma and amyloidosis can also present as large polypoid masses within the bladder[4,5]. Some of these lesions are diagnostically challenging and may have significant therapeutic and prognostic implications if misdiagnosed. Clinical, radiographic and cystoscopic findings in many of these neoplastic and non-neoplastic lesions may be overlapping. Hence, histopathologic examination remains the gold standard for the correct diagnosis.

Here we present a case of a previously asymptomatic elderly male patient who presented with gross haematuria. On cystoscopic examination, the patient was found to have a large (7.3 cm) polypoid mass in the bladder. The patient underwent a transurethral resection of bladder tumour (TURBT) and subsequently had a partial cystectomy including the removal of this large polypoid mass on the basis of the diagnosis rendered on the TURBT specimen.

Case Report

A 71-year-old previously healthy and asymptomatic Caucasian male presented with gross haematuria. Cystoscopic examination revealed a large, pedunculated, smooth and rounded mass present along the left lateral wall of the bladder, posterior to the left ureteral orifice. A transurethral resection biopsy was performed. The polypoid mass was noted to bleed profusely following biopsy. Microscopic examination of the resection specimen revealed numerous spindle-shaped cells in a myxoid background admixed with large foci of necrosis. The spindle cells were small to medium sized with hyperchromatic nuclei and moderate to scant amounts of amphophilic cytoplasm (Figure 1). They were mildly pleomorphic. The spindled cells were admixed with multinucleated osteoclast-like giant cells. Although, numerous mitotic figures were present, no atypical mitoses were identified. No epithelial component was present. Differential diagnoses of IMT, primary bladder sarcoma and sarcomatoid carcinoma were considered based on histological evaluation. Immunohistochemical stains performed showed the spindle cells to be positive for actin (patchy, focal), GATA3 and vimentin. The spindle cells were negative for ALK-1, epithelial membrane antigen (EMA), pan-cytokeratin, cytokeratin 903, p63, CD31, CD34, S100, desmin and p53. The osteoclast-like multinucleated giant cells were positive for CD138. A diagnosis of a malignant spindle cell neoplasm favouring a sarcomatoid urothelial carcinoma or a primary myxoid sarcoma was rendered on initial biopsy specimen. Subsequently, the patient underwent a partial cystectomy with removal of the polypoid mass, resection of the transmural portion of the left ureter, ureteral reimplantation, ureteral stent placement and pelvic lymph node dissection.

Transurethral resection of bladder tumour specimen showing short, mildly atypical spindle cells (haematoxylin and eosin stain, magnification × 40).

On gross examination, there was a large, polypoid, ulcerated mass, 7.3 cm in maximum dimension. The cut surfaces were tan pink to red with cystic and haemorrhagic areas (Figure 2). On frozen section examination, the tumour was composed of malignant spindle cells with foci of osteoid formation. A diagnosis of osteosarcoma was favoured intraoperatively. Microscopic examination of the permanent sections showed predominantly spindle cells admixed with scattered multinucleated osteoclast-like giant cells, which were similar to those seen on the initial biopsy specimen. Foci of necrosis, blood filled spaces and myxoid change were admixed. In addition, there were large areas of osteoid formation (Figure 3). Although the majority of the tumour was composed of an osteosarcoma component, there was a small focus of high-grade urothelial carcinoma present (Figure 4). The tumour did not infiltrate into the muscularis propria.

Cut surface of the large polypoid mass showing large foci of haemorrhage.

Sarcomatous component with osteoid formation (haematoxylin and eosin stain, magnification × 4).

High-grade urothelial carcinoma (lower half) and sarcomatous component (upper half) (haematoxylin and eosin stain, magnification × 4).

Immunohistochemical stains performed showed the sarcomatous component to be positive for vimentin and actin (focal, patchy). GATA3 was positive in both the epithelial and the sarcomatous components. The tumour cells were negative for ALK-1. Pan-cytokeratin (AE1/AE3) immunostain was positive in the epithelial component and negative in the sarcomatous component. Cytogenetic analysis performed on the tumour cells was reported to be normal. A final diagnosis of sarcomatoid urothelial carcinoma was rendered. The patient’s ureteral stent was removed 6 weeks following the partial cystectomy and ureteral reimplantation procedure. Cystoscopy revealed no evidence of early disease recurrence.

Discussion

Neoplastic and non-neoplastic conditions such as urothelial carcinomas, sarcomatoid carcinomas, sarcomas, solitary fibrous tumours, neuroendocrine tumours, IMTs, PSCN, hamartoma and amyloidosis can present as large polypoid masses in the bladder[3]. Other rare lesions presenting as polypoid bladder masses reported in the literature are listed in Table 1. These conditions can simulate each other with overlapping clinical manifestations, imaging and cystoscopic findings. Hence, it is imperative to biopsy these lesions to provide an accurate diagnosis for their adequate management.

Table 1

Rare entities reported in the literature presenting as polypoid bladder masses

Polypoid bladder masses which on microscopic examination are composed of spindle cells include malignant tumours such as sarcomatoid carcinoma and primary sarcoma of the bladder, benign spindle cell tumours such as a leiomyoma, a neurofibroma or a solitary fibrous tumour and non-neoplastic conditions such as IMT and PSCN. It is important to differentiate these because of their therapeutic and prognostic implications[6,7]. Malignant tumours such as sarcomatoid carcinoma and primary sarcomas of the bladder need to be treated more aggressively as compared with the benign spindle cell tumours and non-neoplastic lesions such as IMT and PSCN.

Sarcomatoid carcinoma is microscopically composed of urothelial, glandular or small cell epithelial component and a mesenchymal component that is most frequently an undifferentiated high-grade spindle cell neoplasm which may exhibit different heterologous elements[8]. The key component of differentiating a sarcomatoid urothelial carcinoma from a true sarcoma is to identify the presence of urothelial carcinoma component, no matter how small it may be.

IMTs are typified by a proliferation of myofibroblastic spindle cells and are associated with lymphoplasmacytic infiltrate in a myxoid background. The spindle cells have elongated cytoplasmic processes with enlarged nuclei that may exhibit occasional atypia[9,10,11]. Occasional mitotic figures may be seen, none of which is atypical. Typically, the lesion occurs in young patients with a female preponderance. The spindle cells may be positive for actin and pan-cytokeratin. ALK-1 cytoplasmic staining has been identified in 89% of IMTs[11,12,13,14]. The presence of long spindle cells without atypical mitotic figures, exhibiting immunoreactivity for ALK-1, pan-cytokeratin and actin and the absence of malignant epithelial component are important to distinguish IMT from sarcomatoid carcinomas and sarcomas[12,15,16].

GATA-3, a sensitive urothelial marker and a zinc-finger transcription factor, may play an emerging role in distinguishing sarcomatoid carcinoma from IMT. In a study by Chang et al.[17] GATA3 was positive in 14 of 45 sarcomatoid urothelial carcinomas and only 1 of 23 bladder IMTs stained positive for GATA3. The sarcomatous component in the current case was positive for GATA3. Further investigations are required to study the utility of GATA3 in combination with ALK-1 to distinguish IMT from sarcomatoid carcinoma.

PSCN is usually seen months after surgical instrumentation or resection[13,18,19]. It is composed of fascicles of plump spindle cells with collagen deposition. There may be numerous mitotic figures, none of which is atypical.

Appropriate sampling of these lesions is very important in formulating a correct diagnosis. Selective sampling as in a biopsy specimen or a single frozen section slide may not be representative of all the components of the lesion. This fact is very well illustrated by this case where the resection biopsy specimen had only short spindle cells, based on which a differential diagnoses of a primary sarcoma, or a sarcomatoid carcinoma was favoured over an IMT. The frozen section slide had spindle cells and osteoid, based on which a diagnosis of osteosarcoma was favoured. However, it was only after reviewing multiple sections of the entire mass that a small component of papillary urothelial carcinoma was identified in addition to the spindle cells and osteoid and a final diagnosis of sarcomatoid urothelial carcinoma was rendered.

In limited tissue samples such as bladder tumour biopsies and frozen sections where only spindle cells are present, it is important to determine if the spindle cells are malignant or benign. This can be achieved by paying attention to the histological features as described above. If it is determined that the lesion is malignant, a diagnosis of malignant spindle cell neoplasm can be rendered with a differential diagnosis of sarcomatoid carcinoma versus primary sarcoma. However, in view of the rarity of primary bladder sarcoma, a malignant spindle cell tumour in the bladder of an adult should be considered sarcomatoid carcinoma until proven otherwise. Immunohistochemistry can be helpful as cytokeratin and EMA are strongly expressed in the sarcomatoid carcinoma. This distinction can also be made on the resection specimen after the tumour has been adequately sampled and an epithelial component identified.

Besides sarcomatoid carcinoma and primary osteosarcoma of the bladder, osteoid formation can be seen in urothelial carcinoma with osseous metaplasia[20].

Conclusion

We have discussed the different entities which can present as a large polypoid bladder mass with spindle cell morphology. These entities can range from malignant to benign lesions. Hence, it is very important to distinguish them as it has therapeutic and prognostic implications. It is also important to recognise the limitations of biopsy and frozen section sampling in the evaluation of such lesions. Because primary sarcoma of bladder is extremely rare, thorough examination of the specimen grossly and microscopically to identify urothelial carcinoma is warranted to differentiate it from a more common sarcomatoid urothelial carcinoma.

Consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Abbreviations list

EMA, epithelial membrane antigen; IMT, inflammatory myofibroblastic tumour; PSCN, post-operative spindle cell; TURBT, transurethral resection of bladder tumour.

Authors contribution

All authors contributed to the conception, design, and preparation of the manuscript, as well as read and approved the final manuscript.

Competing interests

None declared.

Conflict of interests

None declared.

A.M.E

All authors abide by the Association for Medical Ethics (AME) ethical rules of disclosure.

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Rare entities reported in the literature presenting as polypoid bladder masses

Lesions presenting as polypoid bladder masses Authors (year)
Seminoma Alsolami et al.21
Malakoplakia Ristic-Petrovic et al.22
Neuroendocrine carcinoma Boyer et al.23
Paraganglioma Bohn et al.24
Endometriosis Lambrechts et al.25
Actinomycosis Bottai et al.26
Polymorphous B-cell lymphoma Sundaram and Zhang.27
Prostatic adenocarcinoma Camilot et al.28
Small cell carcinoma of the bladder Kim et al.29
Melanoma Khalbuss et al.30
Hamartoma of the urachal remnant Park et al.31
Yolk sac tumour of the bladder Taylor et al.32
Keywords