What is Fibrosarcoma?
Fibrosarcomas are a type of cancer composed of fibroblasts, which are cell types that make a protein called collagen, found in our connective tissues. These cancers often have a unique pattern, often described as “herringbone.” Mainly, there are two kinds of fibrosarcomas, one that originates in the bone and the other that starts in the soft tissues. Recently, fewer instances of fibrosarcomas are seen in adults, as more accurate diagnoses mean that tumors similar to fibrosarcomas, but not exact, are better identified.
Fibrosarcomas, furthermore, are split into two types: those that appear in infants or even at birth (infantile or congenital fibrosarcomas) and those seen in adults. The fibrosarcomas in infants seldom spread to other body parts while the ones in adults are highly likely to spread, making them very dangerous.
What Causes Fibrosarcoma?
Fibrosarcomas typically start in the connective tissue that connects muscles and bones (known as fascia) and tendons, but can also happen in bones. It can be a first tumor that starts within the bone’s marrow (the soft, spongey tissue inside the bone), or it can start from an area on the bone itself or show up as a second tumor. Damage to the bone earlier in life – through injuries or radiation therapy – can sometimes lead to fibrosarcomas forming in the bone.
Risk Factors and Frequency for Fibrosarcoma
Adult fibrosarcoma usually occurs in middle-aged and older adults, and it’s rare in children. It’s a bit more common in men and typically affects the deep soft tissues in arms and legs, trunk, and head and neck. In studies of this condition, 80% were classified as high-grade, meaning they are serious. Also, 25% of less serious lesions advanced to high-grade sarcoma as time passed.
In terms of all primary bone tumors, fewer than 5% are fibrosarcomas. Further, only 10% of musculoskeletal sarcomas turn out to be fibrosarcomas. Men are slightly more likely than women to have this bone tumor, and it’s noted that there’s no particular racial group that’s more likely to get it.
The most common sites for these lesions or abnormal areas are the femur (thigh bone) and tibia (shin bone), followed by the humerus (upper arm bone). Typically, these lesions are metaphyseal in origin, which means they start in the part of our bone where growth occurs. These normally start showing up from our twenties up until our seventies.
Signs and Symptoms of Fibrosarcoma
When examining patients, doctors should ask about any soft tissue masses, including their location, size, shape, and texture. They should also check for any old scar tissue, which could be a result of burn injuries. Details about any past surgeries involving vascular grafts, joint prosthetics, or foreign materials should be documented. Additionally, any past radiation therapy can be a risk factor for fibrosarcoma, as well as existing dermatofibrosarcoma or liposarcoma.
Besides, the doctor should examine the regional lymph nodes and check the patient’s neurovascular health. Fibrosarcomas are less common in certain body areas like the retroperitoneum, mediastinum, head, and neck because these tumors typically develop in deep connective tissue rich in collagen. Most fibrosarcomas are round with clear boundaries, firm to touch, and measure from 3 to 8 cm across.
Unfortunately, fibrous tumors often get diagnosed late because they start in deep tissue and cause painless swelling. It is often not until the tumor starts causing symptoms because of its size and location that it gets spotted and diagnosed. Symptoms such as disrupted blood flow, nerve pressure, or limited movement could indicate fibrosarcoma. Late-stage fibrosarcomas can sometimes cause weight loss and loss of appetite. In particular, a painless mass larger than 5 cm could signal cancer and typically needs a specialist’s assessment.
The most frequent symptom of bone fibrosarcomas is a lingering dull pain that may or may not come with swelling. Patients with tumors near joints may experience a limited and painful range of motion.
Testing for Fibrosarcoma
When a doctor suspects a patient may have a type of cancer called a malignant soft tissue tumor based on their medical history and physical exam, the next step is to use radiographic imaging for further investigation.
Contrast-enhanced magnetic resonance imaging (MRI), where a contrast dye is injected into your body to create clearer images, is usually the best tool to examine tumors located in your arms or legs, or in your pelvis. It can provide detailed information about the size of the tumor, its boundaries, its density, how much of it is dead tissue (necrosis), and its blood supply.
In some cases, particularly for tumors located in the back of the abdomen (retroperitoneum) or where involvement of the bones is suspected, computed tomography (CT) scans may be used. Fibrosarcomas, a type of soft tissue cancer, show up on these scans as oval-shaped, clearly defined, and slightly irregular areas. They show signs of pushing aside the surrounding tissues.
If the images suggest cancer, the next step is typically a core needle biopsy, where a hollow needle is used to remove a small sample of the tumor. The sample is then examined under a microscope. This technique is considered more accurate than a simpler method called a fine needle aspiration (FNA), where a slender needle is used to remove cells from the tumor, although FNA can still be helpful in monitoring how a known cancer is progressing, whether it has returned after treatment, or whether it has spread.
If the less invasive biopsy techniques can’t be used or haven’t provided a clear answer, a surgical biopsy may be necessary. If the tumor is relatively small (between 3 cm and 5 cm), it may be recommended to remove the whole tumor as a biopsy (excisional biopsy). If the tumor is larger than that, a piece of it (partial incisional biopsy) might be removed for microscopy.
Fibrosarcomas of the bone can look similar to another type of cancer called an osteoid osteogenic sarcoma on radiographic images. Usually, they appear irregular in shape and show signs of breaking down bone (osteolytic). They don’t cause much visible response from the bone’s outer layer (periosteum), but they often have a “moth-eaten” appearance.
They usually start in the part of the bone containing the growth plate (metaphysis) but can also grow into the bone’s shaft (diaphysis). A certain type of scan using technetium-99m can show an intense area, called a “hot spot,” at the tumor site. Again, MRI often provides the most complete information, including the size of the tumor and whether it affects nerves and blood vessels or extends beyond the bone.
Treatment Options for Fibrosarcoma
Surgical removal is the primary treatment method for localized soft tissue sarcomas, which are a type of cancer that develops in the body’s soft tissues. For tumors that are within a muscle, doctors typically remove the entire tumor along with a portion of healthy tissue around it, a process known as en-bloc excision. There would be no need for additional radiation therapy for these cases.
However, if the tumor has spread beyond the muscle or didn’t originate from the muscle’s endpoints, a more wide-ranging surgical removal can be performed to ensure all the tumor cells are eradicated. As a rule of thumb, surgeons aim to leave a clear margin of about 2 cm around the tumor, but there is no surefire evidence that this is the best margin size. It’s crucial to take into account vital structures around the tumor like nerves and blood vessels.
For larger, high-grade tumors that are over 5 cm in size, a complementary treatment of radiation therapy is strongly recommended. If the surgery does not result in clear margins, meaning some cancer might be left behind, a follow-up operation is usually the next step.
The benefits of using chemotherapy to manage soft tissue sarcomas are unclear, so it’s not routinely used as a standard treatment. Also, fibrosarcomas, a particular type of sarcoma, could become less responsive to specific drugs after using the initial treatment, doxorubicin. For severe cases of fibrosarcoma that require chemotherapy, doctors often start with a class of drugs called anthracyclines. Adding the drugs actinomycin D and ifosfamide can potentially increase the treatment’s effectiveness. However, conventional chemotherapy has only shown improved survival rates in a small percentage of sarcoma patients. Likewise, fibrosarcoma in the bone is treated through multi-drug chemotherapy and wide-ranging surgical removal. These tumors often show a high recurrence rate.
Lastly, directly injecting matrix metalloproteinase inhibitors, such as TIMP-1-GPl fusion protein, into the tumor has reportedly resulted in reduced tumor size and growth, and increased cancer cell death along with reducing the cell’s ability to spread.
What else can Fibrosarcoma be?
Diagnosing fibrosarcoma, a type of cancer, often means ruling out other similar conditions. These include low-grade fibromyxoid sarcomas, sclerosing epithelioid fibrosarcomas, fibrosarcomatous dermatofibrosarcoma protuberans, and synovial sarcomas, which can all be mistaken for true adult fibrosarcoma.
During a microscopic examination of the tissue (known as histology), certain features might suggest that the tumor came from a different type of cancer called dermatofibrosarcoma protuberans. For example, tumors that are CD4-positive (a specific protein found on some cells) might indicate that the cancer came from dermatofibrosarcoma protuberans or started as a single malignant fibrous tumor and progressed to fibrosarcoma.
Finding fibrosarcoma within organs like the heart, lungs, or liver is rare. These cases are likely due to a specific type of cancer that does not produce cytokeratin (a protein found in cells), known as cytokeratin-negative carcinomas. In some cases where the tumor is found in the retroperitoneum (the space in the abdomen behind the intestines), what might initially seem like fibrosarcoma often turns out to be a different type of cancer called dedifferentiated liposarcomas.
What to expect with Fibrosarcoma
As stated before, most adult fibrosarcomas (80%) are identified as high-grade (falling into categories 2 or 3 on the severity scale). Additionally, 25% of those initially identified as low-grade end up progressing, turning into a local recurrence of high-grade fibrosarcoma. Unfortunately, these tumors are aggressive and can often recur in the local area, as well as spread to the lymph nodes and other body tissues.
When it comes to survival rates, the odds for adults with fibrosarcoma are less than 70% after 2 years, and fall to below 55% after 5 years. Comparatively though, fibrosarcomas that occur in soft tissue, as opposed to those growing within bones (intraosseous), are understood to have better outcomes.
Possible Complications When Diagnosed with Fibrosarcoma
The main treatment for fibrosarcoma is surgery, and just like any other operation, it carries risks. These risks could include getting an infection, bleeding, potential damage to nearby tissues or parts of the body, or in severe cases, even death. Additional radiation treatment can also lead to more risks, such as severe tissue scarring or a higher chance of getting a wound infection. For advanced cases of fibrosarcoma, doctors may use chemotherapy. Every type of chemotherapy comes with its own set of risks. However, doxorubicin, the most commonly used treatment, is specifically linked to an increased risk of a heart condition known as dilated cardiomyopathy.
List of potential risks:
- Infection following surgery
- Bleeding during or after surgery
- Possible damage to nearby tissues or parts of the body
- Potential death in severe cases
- Severe tissue scarring with radiation treatment
- Increased risk of wound infection with radiation treatment
- Risks associated with chemotherapy treatments
- Dilated cardiomyopathy with doxorubicin treatment
Preventing Fibrosarcoma
Fibrosarcoma, a type of cancer, often has a challenging outlook because it progresses rapidly. Therefore, it is crucial for patients to have regular medical check-ups and engage in continuous discussion with their main doctor about any unusual soft masses they may find in their bodies during self-examination.
In order to have the best possible results, patients need to seek prompt medical help from medical professionals who are specialized in dealing with tumors affecting muscles and bones.
The best results are often seen when the cancerous tumor is fully removed surgically, with no remaining cancerous cells at the edge of the removed tissue. This is usually followed by additional treatments such as chemotherapy or radiation therapy, which helps to boost the benefits of surgery and reduce the chances of the cancer coming back. Stopping the cancer from spreading to other parts of the body is very important.
