What are the other Names for this Condition? (Also known as/Synonyms)

• SFT of Urinary Bladder
• Urinary Bladder SFT
• Urinary Bladder Solitary Fibrous Tumor

What is Solitary Fibrous Tumor of Urinary Bladder? (Definition/Background Information)

• Solitary Fibrous Tumor (SFT) of Urinary Bladder is a mostly benign (non-cancerous) overgrowth arising from mesenchymal tissue
• The mesenchyme is the middle layer of the 3 primary germ layers of an embryo, namely the ectoderm, mesoderm, and endoderm. The mesoderm gives rise to mesenchymal tissue, which is the source for bone, muscle, connective tissue, and dermis of skin
• Solitary Fibrous Tumors are composed of fibroblasts and related cell types. These rare tumors can occur in any part of the body, or in the soft tissues, where mesenchymal cells are present. The tumor arises in the urinary bladder as a mass
• The cause of formation of the tumor is unknown and currently, no known methods exist to prevent occurrence of the tumor
• Most small tumors are asymptomatic, though the larger ones may compress the surrounding structures and cause related signs and symptoms. The diagnosis of Solitary Fibrous Tumor of Urinary Bladder can be confirmed through a tissue biopsy
• The treatment is complete surgical removal of the tumor with adequate margins. Most Solitary Fibrous Tumors of Urinary Bladder are benign, however some show malignant behavior in terms of recurrence of the tumor after surgery, or metastasis (spread to distant parts of the body)
• The prognosis of Solitary Fibrous Tumor of Urinary Bladder is dependent on whether the tumor can be completely removed through surgery or not

Who gets Solitary Fibrous Tumor of Urinary Bladder? (Age and Sex Distribution)

• The Solitary Fibrous Tumor of Urinary Bladder can present be in individuals between 20 and 70 years of age, but is usually diagnosed in the fifth decade (between 40-50 years)
• In general, both men and women can get it
• Though it is a rare tumor, it can occur worldwide and all races and ethnic groups may be affected

What are the Risk Factors for Solitary Fibrous Tumor of Urinary Bladder? (Predisposing Factors)

• No clear-cut risk factors for Solitary Fibrous Tumor of Urinary Bladder have been established to date

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Solitary Fibrous Tumor of Urinary Bladder? (Etiology)

• Currently, scientists do not know the factor(s) causing Solitary Fibrous Tumor of Urinary Bladder
• Certain genetic mutations are have been detected. Research to characterize these mutations is currently underway

What are the Signs and Symptoms of Solitary Fibrous Tumor of Urinary Bladder?

The signs and symptoms depend on the size of the tumor. Solitary Fibrous Tumors can range in size from a few cm to up to 40 cm; though majority of the urinary bladder tumors are less than 10 cm. They are usually slow-growing and form a single mass. The signs and symptoms associated with Solitary Fibrous Tumor of Urinary Bladder include:

• Small tumors usually do not cause any symptoms. But, occasionally they may become painful, if they compress surrounding structure
• Solitary Fibrous Tumors of Urinary Bladder may occur as slowly enlarging painless mass. The following symptoms may be seen:
  • Frequent urination at night (nocturia)
  • Pain when urinating
  • Difficulty in urinating
  • Hematuria (blood in urine)
  • Urinary tract infection
  • Back pain
  • Weight loss
  • Abdominal pain may occur
• Rarely, these tumors, especially if large, may cause hypoglycemia
  • Hypoglycemia results in Doege-Potter syndrome, which occurs due to secretion of insulin-like growth factor-2 (IGF-2) by the tumor cells (paraneoplastic syndrome)
  • The signs and symptoms of hypoglycemia include confusion, altered mental status, sweating, dizziness, cold hands, etc.

How is Solitary Fibrous Tumor of Urinary Bladder Diagnosed?

The following procedures and tools may be used in the diagnosis of Solitary Fibrous Tumor of Urinary Bladder:

• Evaluation of the individual’s medical history and a through physical examination
• Plain X-ray of the abdomen
• CT or CAT scan with contrast of the abdomen usually shows a well-defined mass, which may have calcifications. This radiological procedure creates detailed 3-dimensional images of structures inside the body
• MRI scans of the abdomen: Magnetic resonance imaging (MRI) uses a magnetic field to create high-quality pictures of certain parts of the body, such as tissues, muscles, nerves, and bones. These high-quality pictures may reveal the presence of the tumor
• Ultrasound scan of the abdomen
• Solitary Fibrous Tumor of Urinary Bladder can additionally be evaluated using angiography of the abdomen region
• MRI scans and PET scans may help differentiate benign versus malignant SFTs by detecting areas of metastasis (if any)
• Cystoscopy: During a cystoscopy, a narrow tube called a cystoscope is inserted to look directly into the bladder. A local anesthetic is usually administered, in order to make the examination more comfortable
• Intravenous pyelogram (IVP): Intravenous pyelogram is a technique using x-rays, to examine the kidneys, bladder, and ureters (the tubes that transport urine from the kidneys to the bladder), by using a dye to highlight the duct systems. Any signs of abnormalities can be visualized using an IVP

Invasive diagnostic procedures such as:

• Laparoscopy: A special device is inserted through a small hole into the abdomen, to visually examine it. If necessary, a tissue sample is obtained for further analysis. Exploration of the abdomen using a laparoscope is called ‘exploratory laparoscopy’
• Laparotomy: The abdomen is opened through an incision for examination, and if required, a biopsy sample obtained. Exploration of the abdomen using laparotomy procedure is called ‘exploratory laparotomy’

Although the above modalities can be used to make an initial diagnosis, a tissue biopsy of the tumor is necessary to make a definitive diagnosis to begin treatment. The tissue for diagnosis can be procured in multiple different ways which include:

• Fine needle aspiration (FNA) biopsy of the tumor: A FNA biopsy may not be helpful, because one may not be able to visualize the different morphological areas of the tumor. Hence, a FNA biopsy as a diagnostic tool has certain limitations, and an open surgical biopsy is preferred. Also, Solitary Fibrous Tumor is a fibrous tumor and FNA usually does not reveal many cells on microscopic examination
• Core biopsy of the tumor
• Open biopsy of the tumor

Tissue biopsy:

• A tissue biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
• Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
• Sometimes, the pathologist may perform special studies, which may include immunohistochemical stains, molecular testing, and very rarely, electron microscopic studies to assist in the diagnosis

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Solitary Fibrous Tumor?

Complications due to Solitary Fibrous Tumor of Urinary Bladder could include:

• Hypoglycemia resulting in Doege-Potter syndrome, which occurs due to secretion of insulin-like growth factor-2 (IGF-2) by the tumor cells
• Recurrence of SFT following surgery
• Malignant transformation resulting in metastatic SFT
• Complications may arise during chemotherapy and radiation therapy, due to the toxic medication or radiation effect

How is Solitary Fibrous Tumor of Urinary Bladder Treated?

There is no standard treatment protocol established for Solitary Fibrous Tumor of Urinary Bladder. However, in majority of cases, a complete surgical excision with clear or wide margins is the preferred mode of treatment, which can result in a cure, especially if it behaves in a benign manner.

The possible treatment measures for Solitary Fibrous Tumor of Urinary Bladder include the following:

• Surgery for early-stage Solitary Fibrous Tumor of Urinary Bladder: If the cancer is small and has not invaded the urinary bladder wall, the surgical treatments a physician may recommend include:
  • Transurethral resection of bladder tumor: Transurethral resection of bladder tumor (TURBT) is a procedure that is frequently used to remove SFT of Urinary Bladder restricted to the inner layers of the bladder. During this procedure, a small wire loop is used to pass through the urethra and into the bladder. This loop uses an electric current (fulguration) to burn away the cancer cells. However, following this procedure, there may be painful or bloody urination
  • Segmental cystectomy: During a segmental cystectomy (also known as partial cystectomy), the part of the bladder that contains the cancer cells is removed by a surgeon. If the cancer is confined to a certain area of the bladder, segmental cystectomy may be an option and a part of the bladder can be removed without damaging bladder function
• Surgery for advanced SFT of Urinary Bladder - if the cancer has invaded deep into the layers of the urinary bladder wall, surgical treatments a physician may recommend include a radical cystectomy (removal of the entire bladder):
  • If the cancer has invaded into the muscle layers, the surgeon may remove the entire bladder, nearby lymph nodes, and a part of the urethra
  • The surgery usually includes removal of the prostate and seminal vesicles in men
  • In women, radical cystectomy involves the removal of the uterus, ovaries, and part of the vagina
• After surgical treatment, the attending physician may discuss the details of the cancer, further treatment measures required, and the post-operative care, with the individual
• Long-term follow-up is required, because recurrence at the site of surgery or metastasis in distant sites have been reported many years after surgery, even with tumors that behave benignly
• Radiotherapy can be used as primary therapy in situations where the tumor cannot be removed completely, or when the tumor reappears (recurrent Solitary Fibrous Tumor of Urinary Bladder) after surgery. Radiation therapy attempts to destroy cancer cells by aiming high-energy beams at the cancer cells
  • Radiation therapy can be administered either by a machine placed outside the body (external beam radiation), or internally, by a device positioned directly at, or close to the malignant tumor. In women, the device is placed inside the vagina (brachytherapy)
  • This technique may be used before surgery, to decrease the size of a tumor, thus allowing for its easy removal; or after surgery, to kill the remaining cancer cells
  • Radiation therapy and chemotherapy are sometimes used as a combination tool 
  • Radiotherapy for SFT can also be used as additional therapy after surgery, if there is a possibility of tumor recurrence after surgery, or if there are inadequate margins (possibility of tumor left behind) following surgery. In some cases due to location of tumor, a complete surgical removal of the tumor is difficult
• Chemotherapy can be used for treating Solitary Fibrous Tumor of Urinary Bladder in following conditions:
  • When the tumors cannot be removed completely (due to incomplete surgical resection)
  • Tumors that recur after surgery (recurrent SFT of Urinary Bladder)
  • Tumors that have spread to distant parts of the body (metastatic SFT of Urinary Bladder)
• Chemotherapy is a treatment that uses drugs to kill cancer cells. In this treatment, combinations of two or more chemotherapy drugs are usually used. These drugs may be administered intravenously (through a vein in the arm), or directly into the bladder (intravesical therapy), by passing a tube through the urethra
• Arterial embolization of Solitary Fibrous Tumor of Urinary Bladder is a possible treatment option. Here the blood supply to the tumor is blocked resulting in tumor death
• Hypoglycemia due to the tumor is treated using corticosteroids
• Post-operative care is important: One must maintain minimum activity levels, until the surgical wound heals

How can Solitary Fibrous Tumor of Urinary Bladder be Prevented?

• Current medical research has not established a way of preventing Solitary Fibrous Tumor of Urinary Bladder formation
• Regular medical screening at periodic intervals with blood tests, radiological scans, and physical examinations, for those who have already endured the tumor, are helpful

What is the Prognosis of Solitary Fibrous Tumor of Urinary Bladder? (Outcomes/Resolutions)

• The most reliable prognostic factor of Solitary Fibrous Tumor of Urinary Bladder is dependent on whether the tumor can be completely removed through surgery with free margins (no traces of the tumor in adjoining tissue) or not
• Current studies show that the tumor does not have any specific histologic feature (when a pathologist examines the tissue under a microscope), which can help in assessing a definite prognosis for the tumor
• Individuals have an overall excellent survival rate following first complete surgical resection
• Solitary Fibrous Tumor of Urinary Bladder that behave malignantly can lead to death
• As with any tumor, it is important to have follow-up appointments with a physician to monitor for any returning tumors

The prognosis of Solitary Fibrous Tumors also depends upon a set of several factors, which include:

• Stage of tumor: With lower-stage tumors, when the tumor is confined to site of origin, the prognosis is usually excellent with appropriate therapy. In higher-stage tumors, such as tumors with metastasis, the prognosis is poor
• The surgical respectability of the tumor (meaning, if the tumor can be removed completely)
• Overall health of the individual: Individuals with overall excellent health have better prognosis compared with those with poor health
• Age of the individual: Older individuals generally have poorer prognosis than younger individuals
• Whether the tumor is occurring for the first time, or is a recurrent tumor. Recurring tumors have worse prognosis compared to tumors that do not recur
• Response to treatment: Tumors that respond to treatment have better prognosis compared to tumors that do not respond to treatment

An early diagnosis and prompt treatment of the tumor generally yields better outcomes than a late diagnosis and delayed treatment.

Additional and Relevant Useful Information for Solitary Fibrous Tumor of Urinary Bladder:

• A tumor is an abnormal growth of tissue arising due to uncontrolled and rapid multiplication of cells that serve no function. They are also called neoplasms. Tumors can be benign or cancerous. A benign tumor may generally indicate no threat to one’s health; it also means that it is not “cancerous”
• Grossly, Solitary Fibrous Tumor of Urinary Bladder is well-circumscribed but not encapsulated, and on cross-section appears gray white to yellow white in color
• Microscopically, benign SFT exhibit alternation of hyper- and hypo- cellular areas, patternless pattern, keloid type collagen, and staghorn-shaped vessels-like areas
• A pathologist may use special studies such as special stains. Special stains (markers) used on biopsy samples may include CD34, CD99, Vimentin, BCL-2. These stains help differentiate Solitary Fibrous Tumors of Urinary Bladder from other benign or cancer lesions
• Although Solitary Fibrous Tumor can be classified as malignant based on the biopsy study (tumor greater than 5 cm, increased mitotic rate, necrosis, increased cellularity, or cytologic atypia, infiltrative growth, and weak CD34), these features cannot be absolutely correlated with regards to how it behaves, the nature of which may be aggressive, metastasis, or recurrent
• Basic fibroblast growth factor (bFGF) labeling index and Ki-67 labeling index can be used for evaluation of benign versus malignant Solitary Fibrous Tumors of Urinary Bladder
• Hemangiopericytoma (also known as Solitary Fibrous Tumor - Hemangiopericytoma type; or Cellular Solitary Fibrous Tumor) is closely related to SFT of Urinary Bladder, but is not identical to it. Many pathologists consider hemangiopericytoma and Solitary Fibrous Tumor as a continuum of tumors