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Malignant Solitary fibrous tumor of the urinary bladder
Running title: Solitary fibrous tumor of bladder
A 55-year old middle-aged woman was detected with a giant pelvic tumor which grew out from the top of the urinary bladder during the CT examination that was done in our hospital one year ago. Our department gave the partial cystectomy and repair. During the surgery, we detected a tumor sized about 4 × 4 × 4.3 cm3 on the right lateral wall of urinary bladder, and it grew out exogenously and surrounded the right ureter without adhesion. The urinary bladder malignant solitary fibrous tumor was verified after immunohistochemistry pathological report.
- 1. Introduction:
Solitary fibrous tumor was an extremely rare interstitialoma. In the past, solitary fibrous tumor was considered as one of the lesion originating from pleura; the tumor found by Klemperer and Rabin in 1931 for the first time originated from pleura (1). For recent years, there have been reports that this tumor occurs to extrapleural regions (4, 5, 6, 7, 8.). Stout and Murray suggested in the following reports (2) that this tumor was gradually considered as the limited or solitary fibrous tumor from pleura and peritoneum to differentiate from the high malignant epithelial mesothelioma with the strongly invasive and proliferative tendency. According to the previous reports, the solitary fibrous tumors were from meninges, cerebral ventricles, eye sockets, nasal cavity and accessory nasal sinuses, retroperitoneal region, thyroid gland, big parotid gland, breasts, liver, mediastina and gastrointestinal tract etc.
- Case report:
A 55-year old middle-aged woman was detected with a giant pelvic tumor which grew out from the top of the urinary bladder during the CT examination that was done in our hospital one year ago. One month before admission, she was detected with pelvic inflammatory disease in pelvic CT examination. No marked signs were seen in physical examination. No hematuria was found in urinalysis, and no relevant uroepithelial tumor cells were detected in urine cytological examination. Tumor markers include AFP, (CA)-125, CA-153, CEA and CA199, which were within the normal range. Abdominal CT examination indicated one giant soft tissue lump, and the largest one had the diameter of about 4.6 cm and grew out from the top of urinary bladder (Fig. 1).
We performed partial cystectomy and repair on the patient. During the surgery, we found that the tumor grew on the right lateral wall of the top of the urinary bladder and surrounded the right ureter. In addition, there were multiple congested vessels in iliac arteries that extended to this tumor. We performed laparoscopic partial cystectomy and the postoperative recovery was smooth. This tumor was a cystic grew-white tumor sized about 4.6× 4 × 4.3 cm3, and the incision was white and multi-nodular. Microscope indicated that this tumor consisted of ovoid cells and spindle cells. This tumor displayed the short sarciniform arrangement in combination with cell high proliferative zone and low proliferative zone as well as the spiral random arrangement (patternless mode). We observed that, the collagen and sclerosing interstitial cells bundles were present between scattered tumor cells. We also observed the branch-like and hemangiopericytoma-like vessels formed the perivascular hyalinization. Mitosis activities >4 mitoses/10 high power field (HPF) (Fig. 2A), and local area cellular heterotype indicated the maglinancy of the tumor. Immunohistochemical examination indicated that the tumor was CD34 strong positive (Fig. 2B) and Ki67 positive degree was very low (Fig. 2C), but CD117, smooth muscle actin and AE1/AE3 were negative.
Up to now, there have been several reports concerning the malignant solitary bladder tumor in English journals, as is shown in Table 1 (6, 9, 10). The long-term prognosis of this tumor is still unknown. The tumor mostly occurs to adults aged between 50 Y to 60 Y (4). The common clinical manifestations of this tumor are pain and palpable lumps. Symptoms of hematuria and anuria are relatively rare and there are also relevant reports. Symptomatic hypoglycemia is associated with the secretion of insulin-like growth factor-2, and this symptom is very rarely found in the solitary fibrous tumor of urinary bladder. The case we are discussing also conforms to this feature. It is known to us that, the case we are discussing is the only patient that presented no clinical symptoms and received partial cystectomy.
The clinical manifestations of the solitary fibrous tumor of the urinary bladder do not have specificity. Generally speaking, the tumor manifestations are the smooth edge, masses abundant in vessels and no invasion to any adjacent tissues and structures. The manifestations under the MRI are equal signal or low signal T1 weighted images, and T1 weighted images were heterogeneous imaging. Heterogeneous appearance might be induced by differentiated cells and collagen content. Very low T2 signals could be observed and due to the Interstitially-rich collagen and fibrotic degenerative tissues. In the case we are discussing, the tumor became markedly enhanced after CT enhancement and also conformed to the feature that the solitary fibrous tumor of urinary bladder is rich in vessels.
The histological feature of the solitary fibrous tumor of urinary bladder is the famose hemangiopericytoma-shaped vascular system usually in combination with perivascular hyaloid degeneration. It is a common manifestation that spindle shaped and monomorphic fibroblasts are distributed between collagens. The polytropy of cells: the cell high proliferative zone and cell low proliferative zone with irregular distribution often become patterns with an irregular distribution (4, 5). The criteria to diagnose this tumor as malignancy include a large volume of tumor (> 10 cm), excessive proliferation of cells, polymorphy of caryon, tumor necrosis, >4 nuclear fission / 10 high-power microscope, and edge infiltration (5). However, solitary fibrous tumor of the urinary bladder can have many forms. Therefore, immunohistochemistry plays a vital role in diagnosis. Tumor cells are often CD34, CD99 and bcl-2, but in the meantime S-100 protein, actin, desmin and keratin negative (4, 5, 6, 7, 8 and 9), and in this case CD34 and Ki67 was diffuse positive.
Gastrointestinal stromal tumor (GIST) is a disease an emphasis should be laid upon in differential diagnosis. Therefore, the histological manifestation of GIST is very similar to that of the solitary fibrous tumor of urinary bladder and GIST can also have positive CD34 and bcl-2. However, GIST often presents the postive CD117. Smooth muscle tumor cells often have cigar-shaped caryons, perinuclear vacuoles and eosinophilic cytoplasm. Although CD34 positive is noted in expression of some leiomyoma cells, and nearly all cells express the smooth muscle actin. Tumor cell expression keratin AE1/AE3 antigen negative, AE1/AE3 antigen is a specific marker of tumor originating from epithelium; this discovery rules out the possibility of malignant tumor. The fusiform cells of this tumor originate from the special comma-shaped nuclei in neurilemma, and CD34 and bcl-2 negative and S-100 positive are often noted in expression in these tumor cells.
Although the solitary fibrous tumors that occur extrapleurally and whose histology indicates the benign solitary fibrous tumor also have the manifestations of malignant tumor, and the incidence rate of local relapse, metastasis and fatality of malignant solitary fibrous tumor is higher. If possible, the complete resection of this tumor is the most recommended treatment at present and this treatment method has a more objective long-term survival rate (4). Adjuvant radiation therapy can be used in some selected patients, but there is still controversy in the efficacy of this method. In contrast, the prognosis of the patients who cannot receive surgical resection of tumor and have tumor relapse and metastasis is relatively poorer. For these patients, radiotherapy can serve as adjunctive therapy or initial treatment. For recent years, anti-angiogenic therapy has been considered as one promising treatment method. Additionally, up to now, there is still lack of evidence for generalized chemotherapy.
We performed partial cystectomy + repair on this patient instead of complete cystectomy because the tumor could be completed resected with smooth edges. During the following 3-month follow-ups, the patient remained healthy. Therefore, for solitary fibrous tumor of urinary bladder, surgery seems to be a relatively reasonable treatment method. However, more clinical data and long-term follow-ups are needed to assess the prognosis of this tumor.
Conflict of interest
None of the contributing authors have any conflict of interest, including specific financial interests or relationships and affiliations relevant to the subject matter or materials discussed in the manuscript.
Figure 1CT¼šCoronal view of the pelvis.
CT plain scan with Parasagittal view.
CT contrast-enhanced scan with Parasagittal view.
Figure 2Tumor exhibits high cellularity and is composed of spindle to oval cells arranged in short, ill-defined fascicles with nuclear atypia and three mitoses, staghorn vessels, and interstitial hyalinization (H&E stain, 200×).
Tumor cells exhibit diffuse positivity for CD34 (immunohistochemical stain, 200×).
Tumor cells exhibit diffuse positivity for Ki67 (immunohistochemical stain, 200×).
Table 1. Clinical data of the reported 16 cases of solitary fibrous tumor of the urinary bladder.