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

• Pleural SFT
• Pleural Solitary Fibrous Tumor
• SFT of Pleura

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

• Solitary Fibrous Tumor (SFT) of Pleura is a mostly benign (non-cancerous) overgrowth arising from the 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 as a mass from the pleural surface (the lining of the lungs)
• The cause of formation of the tumor is unknown. 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 Pulmonary Solitary Fibrous Tumor can be confirmed through a tissue biopsy
• The treatment is complete surgical removal of the tumor with adequate margins. Most Solitary Fibrous Tumors of Pleura 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 Pleura is dependent on whether the tumor can be completely removed through surgery or not

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

• Solitary Fibrous Tumor of Pleura can be present 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 Pleura? (Predisposing Factors)

• No clear-cut risk factors for Solitary Fibrous Tumor of Pleura 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 one's 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 Pleura? (Etiology)

• Currently, scientists do not know the factor(s) causing Solitary Fibrous Tumor of Pleura
• 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 Pleura?

The signs and symptoms depend on the size of the tumor. Solitary Fibrous Tumors can range in size from 2 cm to 20 cm. They are usually slow-growing and form a single mass. The signs and symptoms associated with Solitary Fibrous Tumor of Pleura include:

• Small tumors usually do not cause any symptoms. But, occasionally they may become painful, if they compress surrounding structure
• Solitary Fibrous Tumors of Pleura may occur as slowly enlarging painless mass
• The tumors are generally located in the pleura or lining of the lung (in about 95% of the cases); in rare cases, they may be present in the lung tissue (lung parenchyma)
• There may be non-specific symptoms such as chest pain and cough
• Breathing problems, such as rapid breathing and shortness of breath, can also 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 Pleura Diagnosed?

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

• Evaluation of the individual’s medical history and a through physical examination
• Plain x-ray of the chest
• CT or CAT scan with contrast of the chest 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 lungs: 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
• Pulmonary Solitary Fibrous Tumor can additionally be evaluated using angiography of the chest region
• MRI scans and PET scans may help differentiate benign versus malignant SFTs by detecting areas of metastasis (if any)

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
• Open lung biopsy
• Thoracoscopy: A medical instrument called a thoracoscope is inserted into the chest through tiny incisions, in order to examine and remove tissue from the chest wall, which is then analyzed further
• Thoracotomy: Thoracotomy is a surgical invasive procedure with special medical instruments to open-up the chest and remove tissue from the chest wall or the surrounding lymph nodes of the lungs
• Mediastinoscopy: A medical instrument called a mediastinoscope is inserted into the chest wall to examine and remove samples

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 of Pleura?

Complications due to Solitary Fibrous Tumor of Pleura 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
• Pleural effusion
• 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 Pleura Treated?

There is no standard treatment protocol established for Solitary Fibrous Tumor of Pleura. 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.

• 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 Pleura) after surgery
• 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 Pulmonary Solitary Fibrous Tumor in following conditions:
  • When the tumors cannot be removed completely (due to incomplete surgical resection)
  • Tumors that recur after surgery (recurrent SFT of Pleura)
  • Tumors that have spread to distant parts of the body (metastatic SFT of Pleura)
• Arterial embolization of Solitary Fibrous Tumor of Pleura 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 Pleura be Prevented?

• Current medical research has not established a way of preventing Solitary Fibrous Tumor of Pleura 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 Pleura? (Outcomes/Resolutions)

• The most reliable prognostic factor of Solitary Fibrous Tumor of Pleura 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 Pleura 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 Pleura:

• 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 Pleura 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, pattern-less 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 Pleura 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 Pleura
• Hemangiopericytoma (also known as Solitary Fibrous Tumor - hemangiopericytoma type; or Cellular Solitary Fibrous Tumor) is closely related to SFT of Pleura, but is not identical to it. Many pathologists consider hemangiopericytoma and Solitary Fibrous Tumor as a continuum of tumors