Solitary Fibrous Tumors

What is Solitary Fibrous Tumors?

Solitary fibrous tumors (SFTs) were first discovered in the early 20th century by Klemperer and Rabin, who noticed certain unique characteristics of these tumors in the lining of the chest cavity in 1931. At first, these tumors were called “solitary (localized) mesothelioma of pleura” by Stout and Murray in 1942, but this name was changed to “solitary fibrous tumor” by Stout and Hamidi in 1951. Stout and Murray also made strides in understanding tumors called “hemangiopericytoma” (HPC), coming up with ways to diagnose and assess the severity of them. Initially, these tumors were only seen in the chest cavity and lungs, but we started seeing them in other parts of the body from 1991 onwards.

SFTs are a type of tumor that can turn up anywhere in the body, but is most commonly found in the abdomen. These tumors comprise only 3.7% of all soft tissue tumors. They’re complex because they can look a lot like other tumors, meaning they can be difficult to accurately identify. Diagnosing them correctly is essential, however, as it affects the course of treatment and the outlook for the patient. Though SFTs usually follow a slow course and often don’t cause symptoms, diagnosing can be a challenge despite the distinctive pattern SFTs usually show on medical tests. Recently, the discovery of a marker called NAB2-STAT6 gene fusion has improved our ability to diagnose these tumors. However, there is still work to be done on understanding if this marker can confidently distinguish SFTs from other types of tumors.

What Causes Solitary Fibrous Tumors?

The exact causes of Solitary Fibrous Tumors (SFTs) are not completely understood, but they are believed to develop from cells of a certain type called mesenchymal cells. Some studies indicate that changes in the DNA, specifically the merging of two genes, NAB2 and STAT6, which are found on a part of chromosome 12, play a key role in the development of these types of tumors.

So far, there haven’t been any environment-related factors discovered that increase the risk of getting SFTs. There might be other factors at play, like hormonal influences and certain genetic predispositions, that could contribute to the development of SFTs. But we still need more research to further pinpoint the exact causes and mechanisms behind these tumors.

Risk Factors and Frequency for Solitary Fibrous Tumors

Solitary fibrous tumors (SFTs) can occur anywhere in the body. On average, one new case is reported per million people each year. The most common location for these tumors is the pleura, which accounts for roughly 30% of cases. However, pleural SFTs make up less than 5% of all pleural tumors. Other common locations for SFTs include the meninges, the abdominal cavity, the trunk, the extremities, and the head and neck.

SFTs mostly occur in adults between the ages of 20 and 70, and are generally rare in children and teenagers. Pleural SFTs typically appear at an older age (around 60.2 years) compared to meningeal (around 50.6 years) and extrapleural SFTs (around 50.3 years). Additionally, these tumors are equally likely to occur in both men and women.

• Solitary fibrous tumors (SFTs) can occur anywhere in the body.
• The average annual incidence rate is 1 new case per million people.
• The most common location of these tumors is the pleura, accounting for about 30% of the cases.
• Pleural SFTs constitute less than 5% of all pleural tumors.
• Other common locations include the meninges (27%), the abdominal cavity (20%), the trunk (10%), the extremities (8%), and the head and neck (5%).
• SFTs most commonly occur in adults between 20 and 70 years old and are rare in children and teenagers.
• The average age of people with pleural SFTs is about 60.2 years, while those with meningeal and extrapleural SFTs are around 50.6 years and 50.3 years, respectively.
• Both men and women can have SFTs.

Signs and Symptoms of Solitary Fibrous Tumors

Doctors take a careful approach when checking a patient who might have a Solitary Fibrous Tumor (SFT). This process includes gathering a detailed health history and performing a comprehensive physical examination. The reported symptoms of SFTs could vary based on where they are located. However, they generally cause pain, a noticeable lump, and often nerve or blood vessel issues. If the tumor is in the belly or pelvic area, symptoms may also involve difficulty with urination and bowel movement.

During the consultation, the doctor will ask the patient about certain symptoms like pain, swelling, changes in bowel or bladder habits, which might imply the presence of a tumor. The patient will also be questioned about symptoms like low blood sugar levels and joint pain that could be connected to a disease condition associated with the tumor. It’s also important to share any relevant medical history, including any previous surgeries or exposure to radiation.

In the physical check-up, the doctor will pay particular attention to where they suspect the tumor might be and any associated findings. They might feel a firm, non-tender lump when touching the area. This could change depending on the size and place of the tumor. Other signs they’ll look for include skin changes such as redness or sores covering the lump, and any signs of compromisation to the nerves or blood vessels, particularly if the tumor is in a critical location.

The doctor will not only examine the local area but also conduct a thorough overall examination. This is to check for signs the disease may have spread to other parts of the body or disease conditions associated with SFTs. They’ll check neurologic function, respiratory function, look for changes in the fingernails, and check for symptoms suggesting hormone-related dysfunction.

• Gather comprehensive health history
• Perform detailed physical examination
• Question about symptoms like: pain, swelling, changes in bowel or bladder habits
• Ask about low blood sugar levels and joint pain
• Share any relevant medical history
• Physically check the suspected area for a lump
• Look for skin changes over the lump
• Check for any nerve or blood vessel issues
• Perform comprehensive overall examination
• Check for signs of disease spread
• Assess neurologic and respiratory function
• Inspect fingernails for changes
• Evaluate for symptoms of hormone-related dysfunction

Taking a detailed history and performing a thorough physical examination are critical steps in identifying potential signs and symptoms associated with SFTs. This will guide further diagnostic tests and help determine the best management strategies.

Testing for Solitary Fibrous Tumors

When a doctor suspects that a patient might have a specific type of tumor called Solitary Fibrous Tumors (SFTs), the first step in the diagnosis usually involves getting some scans done. These could include CT scans or MRIs. These scans can locate the tumor, see how big it is and understand if it has affected any other body parts. Sometimes, other scans like 18F-FDG PET/CT and ultrasound could also be useful.

The preferred way to initially identify an SFT is through a CT scan. If approximately 65% of the cases, these tumors show a lot of blood vessels. Sometimes, heterogeneity, which means difference in enhancement, is more common in aggressive (complex) SFTs than in the slower (indolent) SFTs. In other words, aggressive SFTs look different on the scan compared to slower ones. Most often, SFTs look like well-defined masses that show a lot of blood vessels and have varying degrees of cystic change and necrosis, which means tissue death. Regardless, CT scans cannot point out SFT with 100% surety.

Now, if we move on to MRI, SFTs have different appearances. The solid parts of these tumors appear isointense on T1-weighted images, which means they have the same intensity as the skeletal muscle, while the cystic areas appear hyperintense on T2-weighted sequences. This is important in distinguishing SFTs from other masses. They appear strongly enhanced upon contrast administration, but again, this is common in their type (vascular).

The 18F-FDG PET/CT scans aren’t described a lot in SFT-related literature, but some studies suggest that benign (non-cancerous) SFTs show mild activity while malignant (cancerous) SFTs show strong homogeneous hypermetabolism. These scans can be helpful when there is suspicion of spread or recurrence of these tumors.

The ultrasound could be used based on the location of the tumor. For instance, this method was used in one particular case where the patient had a palpable breast mass.

However, although all these methods are useful, they can only suggest that the patient might have an SFT. The final, definitive diagnosis requires a histologic confirmation. This is usually achieved through a core-needle biopsy, where a sample of the tissue is taken out and examined under a microscope by a pathologist. This examination helps understand the type of cells in the tissue, their arrangement, and can help identify any specific markers that are characteristic of SFTs. Occasionally, a procedure called an open incisional or excisional biopsy might be necessary. This involves either removing a small portion of the tumor tissue or removing the entire tumor for examination and to confirm the diagnosis.

In short, diagnosis of SFTs involves many steps including clinical assessment, imaging studies, and biopsy. These steps are necessary for the confirmation of diagnosis and understanding of the extent of disease spread, with the goal of optimizing treatment decisions and patient outcomes.

Treatment Options for Solitary Fibrous Tumors

There is no universally agreed-upon method for treating solitary fibrous tumors (SFTs) due to their infrequent occurrence and lack of extensive research. Currently, the most effective treatment is surgery to remove the tumor. However, the impact of other treatments like radiation or chemotherapy is still not fully known. Some reports suggest that radiotherapy (a treatment using radiation) can be successful in managing SFTs. Similarly, certain chemotherapeutic and novel targeted drugs could have some positive effects on SFTs. However, there’s no general agreement on these methods’ effectiveness. The best treatment process and results for patients with SFTs typically result from close cooperation among different medical specialties.

For Surgery, the main form of treatment for localized SFTs and in cases where the disease has spread to only a few areas involves removing the tumor and a surrounding area free of tumor cells. The specifics of the surgery can vary depending on the tumor’s location, such as thoracic SFTs (in the chest), abdominal SFTs (in the abdominal cavity), meningeal SFTs (on the dura mater, a membrane that covers the brain and spinal cord), or extremity SFTs (on the limbs). Because SFTs are highly vascular (rich in blood vessels), they may recommend a procedure called embolization before surgery to make the operation safer by reducing blood supply to the tumor.

The use of radiation treatment, either before (neoadjuvant) or after (adjuvant) surgery, is not backed by prospective study data. It may serve as an option to control the local tumor, especially those with a high risk of recurrence. However, decisions regarding radiation treatment should be personalized for each patient after detailed discussions among the medical team.

Chemotherapy, a treatment using drugs to kill cancer cells, has traditionally been used in managing advanced or metastatic SFTs (where the tumor has spread to other parts). Again, the effectiveness of chemotherapy is not conclusively proven, mainly due to the lack of clinical trials specific to SFTs. Hence, its optimal use remains uncertain. The treatment approach and results have shown variability among different categories of SFTs. More research is needed to establish the most effective chemotherapy regimens for managing SFTs.

Targeted therapies, especially those aimed at factors contributing to tumor growth, have shown promise. The antiangiogenic agents inhibit the growth of new blood vessels, thus starving the tumor of its nutrients. However, these results are from early investigations, and more research is needed to validate these findings and to determine the best treatment approaches. If appropriate, patients are encouraged to participate in ongoing clinical trials.

What else can Solitary Fibrous Tumors be?

Solitary fibrous tumors (SFTs) are difficult to diagnose because they resemble many other types of soft tissue tumors. That’s why they’re sometimes called “the great simulator”. Doctors use a variety of techniques including study of the disease’s clinical course, microscopic analysis of the tissue (histomorphology), and specialized tests (immunohistochemical and molecular characteristics) to make an accurate diagnosis. Here are some possible conditions that doctors need to rule out when diagnosing an SFT:

• Gastrointestinal stroma tumor
• Leiomyosarcoma
• Schwannoma
• Fibromyxoid sarcoma
• Myofibroblastoma
• Angiofibroma
• Fibroblastic spindle cell tumor
• Spindle cell lipoma
• Fibroma
• Pseudoangiomatous stromal proliferation
• Synovial sarcoma
• Malignant mesothelioma
• Sarcomatoid mesothelioma
• Desmoid tumor
• Neurogenic tumors
• Lymphoma
• Soft tissue sarcoma
• Deep fibrous histiocytoma
• Dedifferentiated liposarcoma
• Malignant peripheral nerve sheath tumor
• Dermatofibrosarcoma protuberans
• Metastases

What to expect with Solitary Fibrous Tumors

Solitary fibrous tumors (SFTs) are a type of tumor that can have a range of effects, from pretty harmless to possibly more aggressive. Although it’s tricky to guess how an SFT will behave, most of these tumors are harmless. However, some may come back even after being treated and initially classified as harmless. On the bright side, when we compare SFTs to many other types of tumors, people with SFTs usually have a better outlook. Some live for over 5 years after being diagnosed, and others for over 10 years. The tumor’s location can play a big role in this outlook as well. Tumors found outside the chest area, such as those in the brain coverings (meninges), pelvis, behind the abdominal cavity (retroperitoneum), and mediastinum (area in the chest containing the heart, large blood vessels, windpipe, esophagus, and thymus), often come back more often and possibly have a worse outlook than tumors in the chest area. In particular, SFTs in the meninges often have more cells and higher cell division rates, adding to a worse outlook than SFTs outside the meninges.

Now, there are various factors that can give us clues about the outlook in SFTs. Findings have shown that tumors that come back, tumors that still have some cells left after surgery, tumors larger than 10 cm, presence of more than 4 mitoses (cell divisions) per 10 high-power microscope fields, increased variation in cell structure and size, higher cellularity (more cells), and the presence of malignant (cancerous) components all point to a poor outlook. Other things like tumor death or bleeding, increased cellularity, and variation in cell structure and size have also been linked to worse behaviors and worse outlooks.

To give patients and doctors a clearer picture of what to expect and guide decisions about treatment, Demicco and his team suggested a model to categorize patients into low-, intermediate-, and high-risk categories, based on the patient’s age, tumor size, and the number of mitoses. This model offers a foundation to estimate how the disease might progress and guide treatment decisions in patients with SFTs. A complete look at these factors is important to classify risk and guide treatment for the best potential outcome.

Possible Complications When Diagnosed with Solitary Fibrous Tumors

Solitary fibrous tumors (SFTs) can lead to diverse complications due to their size, location, and nature. Various common issues that accompany SFTs are:

• Local invasion: SFTs can spread into nearby tissues and organs. This can cause compression, shifting, or invasion resulting in discomfort, blockage, or functional disorders of affected areas.
• Compression symptoms: SFTs can squeeze nearby structures, nerves, or blood vessels because of their size and location. This can lead to discomfort, neurological problems, or compromised blood flow.
• Hemorrhage or necrosis: Larger SFTs may exceed the capacity of their blood supply. This can result in hemorrhage or cell death within the tumor, possibly initiating acute symptoms such as discomfort, unstable circulation, or indications of organ dysfunction.
• Functional Impairment: SFTs located in crucial places, like the central nervous system or major blood vessels, can disrupt organ function or cause neurological deficits.
• Obstructive symptoms: SFTs positioned in the abdomen or similar areas could obstruct the gastrointestinal tract, urinary pathway, or bile ducts. This can cause symptoms such as abdominal discomfort, vomiting, or jaundice.
• Paraneoplastic syndromes: Exceptionally, SFTs can produce hormones that result in specific syndromes such as Doege-Potter syndrome or Pierre-Marie Bamberger syndrome.
• Treatment Complications: Various causes such as wound infections could also lead to complications during surgery, radiation therapy, or systemic treatments.
• Recurrence: Despite complete surgical removal, there’s still the risk of SFTs reappearing in the same location.
• Metastasis: Malignant SFTs can spread to far-off organs, causing the growth of tumors at these sites, leading to additional complications and a worsening prognosis.
• Psychological Impact: Dealing with a diagnosis of SFT can lead to psychological consequences such as anxiety, depression, or emotional distress.

Overall, the issues associated with SFTs can widely vary and depend on different factors such as the characteristics of the tumor, its location, and the patient’s personal aspects. Early detection and comprehensive evaluation are vital to minimize these complications and provide the best possible outcome.

Recovery from Solitary Fibrous Tumors

For patients who have undergone surgery to remove SFTs (Solitary Fibrous Tumors), regular check-ups are very important. These check-ups help doctors spot and treat any return of the cancer (which happens in about 8% of cases) or any spread of the disease early on. Since SFTs are not common, there isn’t a standard set of rules for these check-ups. Various research groups have tried to come up with guidelines for post-surgery check-ups, but the results have varied.

A study from the MD Anderson Cancer Center found certain factors that are linked with the cancer spreading. These include a tumor size greater than 15 cm, being older than 55, and a high rate of cell division (more than 4 divisions per 10 microscope fields). Patients with these risk factors should have very regular check-ups.

Usually, post-surgery checks involve taking images of the place where the tumor was every 3 to 4 months for the first 2 years after surgery, then every 6 months for the next 3 years. After 5 years, it might not be necessary to continue the imaging tests, as it’s unusual for the cancer to return at this stage. However, the check-up schedule should be customized for each patient based on the location of the tumor and other individual factors. Given that SFTs can come back many years after the first diagnosis and treatment, lifelong check-ups might be necessary for some patients.

Preventing Solitary Fibrous Tumors

Stopping Solitary Fibrous Tumors (SFTs) at their earliest stage and educating patients about them are critical for quick treatment and prevention of complications. Raising awareness about SFTs through campaigns aimed at the general public and medical professionals can make an early diagnosis more likely. These campaigns might spread information about what can increase the risk of getting SFTs, common signs to look out for, and why regular doctor visits are essential to catching these tumors early.

By learning about factors which could increase the chance of getting SFTs – things like age, gender, and exposure to specific types of environments – patients can understand if they’re at higher risk and seek help sooner if they notice worrisome signs. Knowing about SFTs’ common signs, like feeling a lump, pain or other unexplained things happening in the body, can help people to understand they need to see a medical professional for a deeper check-up. Understanding that finding a disease early and getting treatment soon can improve the chances of recovery might encourage individuals to see their doctor straight away if they notice any unusual changes in their health.

Educating patients about how doctors diagnose SFTs can help them feel more comfortable. Diagnostic procedures might involve taking pictures of the inside of the body (for example, with MRI or CT scans) and taking a small tissue sample to examine (a biopsy). Knowing why doctors perform these tests – to confirm a diagnosis and make decisions about treatment – can help patients understand their purpose. Giving information about what kind of treatments are available for SFTs, including operations to remove them, treatments using radiation or treatments with medications to kill the cancer cells (chemotherapy), might help patients feel able to make decisions about their care alongside their healthcare providers. Encouraging patients to stay on top of their health by not missing any follow-up visits and by keeping up with their ongoing imaging scans after completing their treatment is essential. This can ensure that if the SFTs come back or there are any complications, doctors can find them early and address them quickly.

Linking patients and their families to resources like organisations which advocate for patients’ rights and support groups can be highly beneficial. They can provide emotional support and practical help throughout the different stages of treatment. Encouraging patients to lead a healthy lifestyle – like eating a balanced diet, doing regular physical activity and avoiding smoking and heavy drinking – might help with their overall health and might even lower their chance of the SFTs returning. Patients should also know about clinical trials that are currently ongoing to explore new ways to treat SFTs. Joining these trials can give them a chance to take part in research and get hold of new treatments that aren’t yet available through normal treatment options.