Synovial sarcoma of the joints: characteristics, clinical picture, diagnosis and treatment

In oncological practice, malignant neoplasms of soft tissues are quite common. Soft tissue sarcomas include malignant tumors localized in the synovial membranes, adipose, muscle, and epidermoid tissues. Among this type of sarcoma, in approximately 5-10% of cases, synovial sarcoma occurs, which is otherwise called malignant synovioma or synovioblastic sarcoma.

• What kind of pathology
• Etiology and pathological anatomy
• Localization and epidemiology of the tumor
• Clinical manifestations
• Sarcoma of the knee joint
• Ankle sarcoma
• Elbow sarcoma
• Shoulder sarcoma
• Soft tissue sarcoma
• Diagnostic methods
• Treatment of synovial sarcoma
• Forecast

What kind of pathology

According to the WHO definition, synovial sarcoma is a mesenchymal spindle cell malignancy that may have a tissue component with epithelial differentiation and the presence of a specific chromosomal translocation. This term first appeared back in 1895: it was introduced by the German doctor G. Simon. Since then, several hundred cases have been described, which have brought synovial sarcoma into an independent nosology.

Despite its name, the origin of malignant synovioma from elements of the synovial membrane has not been confirmed. It is believed that this tumor is a variant of primary carcinosarcoma. Some scientists believe that it comes from immature mesenchymal cells. There is even evidence that the tumor may be of neuroectodermal origin (due to the similarity in the expression of many genes of synovial sarcoma with a malignant tumor originating from the sheaths of nerve fibers). Be that as it may, research into the origin of the cells of this neoplasm continues, and in the WHO classification it is in the section of tumors with unclear tissue differentiation.

Etiology and pathological anatomy

The etiological factors of synovial sarcoma, like almost all cancers, are not completely clear. Precancerous conditions (schwannoma, dysplasia of tissues adjacent to the tumor), constant severe trauma to the joints, and the presence of foreign bodies are described as the possible causes of this type of sarcoma.

On microscopic examination of a biopsy specimen, a typical finding will be spindle cells with glandular-like structures. In terms of its morphological characteristics, malignant synovioma is extremely diverse: under a microscope, between poorly differentiated round-shaped cells (or resembling epithelium), you can see cracks or cavities that are filled with mucus-like structures. With a predominance of papillary elements like synovial villi, the tumor is classified as fibrous. The neoplasm may have many glandular cells, and then it is called cellular synovial sarcoma. If we consider the WHO data, then its experts divide this tumor into monophasic spindle-shaped and biphasic histological subtypes. Determining the exact morphological variant of the neoplasm is important for further prognosis.

Can osteosarcoma be prevented?

The likelihood of developing many cancers in adults can be reduced through lifestyle changes such as maintaining a healthy weight, eating right, getting enough physical activity and quitting smoking. Unfortunately, osteosarcoma cannot be prevented in this way.

Most known risk factors, such as age, gender, bone diseases and hereditary disorders, cannot be changed. With the exception of exposure to radiation, including that received during radiation therapy, there are no other known and preventable causes that can provoke this type of cancer.

Localization and epidemiology of the tumor

Synovial sarcoma is one of the most common malignant neoplasms of soft tissue among the adult population, and in children it is in second place (in terms of occurrence) after rhabdomyosarcoma. The tumor is most often found in young people aged 15 to 35 years, less often in patients under 50 years of age. After this age threshold, it practically does not occur. There is a slight predominance of the tumor in men.

The favorite location for synovial sarcoma is the soft tissue of the extremities, and sarcoma is localized in the joint area in 40% of cases. The knee joint is most often affected (30% of all joint locations), then the ankle joint, hip joint, and very rarely in the joints of the upper extremities. In most cases, metastases of synovioma (its malignant form) are found in the lungs (60-80%), in regional lymph nodes (up to 40%), and less often in the bones. Tumor metastasis occurs through the lymphogenous route.

Stages of osteosarcoma

Immediately after identifying a tumor, doctors determine its stage - find out how much tissue has been affected by the disease. This information is very important for specialists, since it allows them to evaluate approximate prognoses and, based on them, select the most appropriate treatment for each individual patient.

Staging of osteosarcoma is carried out according to the international TNM system, which takes into account data from several key factors:

• " T
  ": size of the main tumor;
• “ N
  ”: the number of damaged nearby lymph nodes - tiny lymphatic organs. The lymphatic system complements the cardiovascular system. The lymph circulating in it - the intercellular fluid - washes all the cells of the body and delivers the necessary substances to them, taking away waste. In the lymph nodes, which act as “filters,” dangerous substances are neutralized and removed from the body. systems that retain and neutralize harmful substances;
• “ M
  ”: the presence or absence of metastases - additional cancerous tumors in organs and tissues located far from the main focus of the disease.

Another important point is the degree of differentiation

tumors:
G1 – highly differentiated
: its cells are very similar to normal ones, grow slowly and respond well to treatment.
G2 – moderately differentiated
: they are noticeably different from healthy ones, develop faster and respond worse to therapy.
G3 – low differentiated
: cells are little similar to ordinary ones.
G4 – undifferentiated
: in them it is almost impossible to guess the “source” cells from which they turned into tumor cells. Tissues consisting of them usually develop rapidly and respond poorly to treatment.

Based on differentiation, doctors determine the degree of malignancy

neoplasms:

• Low grade, G1 and G2
  : contain few dividing, healthy-like cells and grow slowly.
• High-grade malignancy, G3 and G4
  - develop rapidly. Their tissues contain many dividing, multiplying very quickly, and are not similar to normal cells. Most tumors found in children and adolescents fall into this category.

Stages of osteosarcoma:
IA
.
There is only one main focus, and its dimensions do not exceed 8 centimeters. The remaining organs are healthy, the degree of malignancy is low. IB
.
One tumor is larger than 8 cm, the degree of malignancy is low. IIA
.
One high-grade tumor up to 8 cm in diameter. IIB
.
One high-grade lesion measuring more than 8 cm. III
.
Several individual osteosarcomas of any grade of malignancy in one area - the one in which the first tumor appeared. IVA
.
Neoplasm of any degree of malignancy and volume. Metastases were found in the lungs - additional foci of cancer. IVB
. The size of the main tumor and its degree of malignancy can be any. The disease may have affected the lymph nodes. Metastases are present in other organs and tissues located in various areas of the body.

Clinical manifestations

Symptoms of synovial sarcoma begin with the onset of pain in the area of ​​the affected joint or soft tissue. If the tumor is dense and has calcifications, then the pain syndrome is more pronounced, and if it is cystic, the pain is not so noticeable. As the tumor progresses and surrounding tissues (vessels, synovial membranes, bone tissue) are involved in the oncological process, the pain increases. It is accompanied by a limitation in the range of both active and passive movements of the affected joint.

Upon palpation, a dense or soft (depending on the structure) formation is determined, sometimes without clear boundaries. The diameter of the tumor varies widely: from 2-3 to 20 cm. General symptoms characteristic of cancer of any location and origin increase quite quickly: periodic increase in body temperature, often to low-grade and febrile levels, malaise, weakness, loss of appetite, decreased weight.

Types of soft tissue cancer

The most common type of skin cancer is basal cell carcinoma . This is a thickened area of ​​skin that has a normal color or a pearly-waxy tint. Typically found in the arms, neck or head, up to 20% of lesions are found on the remaining parts of the body.

Another option for skin lesions is squamous cell carcinoma , which looks like a non-healing ulcer, spots with detachment of epithelial scales, and compacted reddened tubercles. The most common localization is the back and chest area, face or arms, neck, ears.

Another type - the most aggressive - is melanoma , a tumor that occurs in the area of ​​moles (pigmented areas of the skin). It is characterized by rapid progression and high malignancy. Usually located in the interdigital spaces, in the groin, on the head, torso, and back.

Sarcoma of the knee joint

One of the very first and often dominant signs of sarcoma of the knee joint is local pain. With the rapid growth of the tumor (and the malignant course of sarcoma is most often aggressive), deformation of the knee joint appears, which can be distinguished visually: the appearance of a lump, redness, and then bluishness of the skin over the site of the lesion.

Impaired functionality increases as the tumor progresses: the range of movements decreases, the person begins to limp. Limiting physical activity brings only temporary relief. Sarcoma is characterized by constant pain, especially at night. As the malignant process spreads to the surrounding tissues, swelling increases, which often “drains” down along the blood, lymphatic vessels and nerves. Increasing pain and the inability to relieve it with non-narcotic analgesics indicate tumor growth.

Signs and symptoms of osteosarcoma

As a rule, the disease is detected when the symptoms it causes appear, which depend on the location of the tumor:

• The most common sign of osteosarcoma is pain
  in the affected area. It may not be constant and worsen at night or with physical activity if the tumor is in the leg.
• Another possible warning sign that appears later is edema
  , caused by tissue damage and impaired fluid outflow.
• Lameness
  that develops over time .
• Restriction of joint movement
  .
• Swelling
  and
  redness of the skin
  over the site of the disease.
• Reduced density of bones affected by osteosarcoma leads to fractures
  .

Elbow sarcoma

A malignant neoplasm of this localization most often appears in the process of metastasis of other sarcomas. At the onset of the disease, pain gradually develops, and swelling can be visualized and palpated. Due to the fact that there is a powerful neurovascular bundle in the cubital region, the pain quickly acquires an acute, burning character. When the tendons and synovial membrane of the capsule are involved in the process, the motor function of the elbow joint is disrupted, then numbness of the limb and fingers increases when nerve fibers are damaged. Involvement of bone tissue in the process due to the aggressiveness of tumor growth leads to the frequent occurrence of pathological fractures.

Diagnostic methods

Since the onset of synovial sarcoma can be disguised as rheumatological diseases of the joints, it is important to conduct a full range of instrumental and laboratory studies. Radiation diagnostic methods (x-ray examination in at least two projections and computed tomography) make it possible to identify foci of tumor formation and the presence of calcifications, which are often located in the central part of the sarcoma during its long-term course. In many cases, X-ray images reveal destructive processes in the adjacent bone tissue.

Angiography shows pathological proliferation of blood vessels in the affected area. Radioisotope research with strontium can help determine the exact location of the neoplasm and its boundaries, which is important for determining the scope of organ-preserving surgery.

A biopsy of the lesion will help differentiate synovial sarcoma not only from other tumors and non-oncological diseases, but also to determine the histological subtype of cancer.

Diagnosis of osteosarcoma

The examination is a very important moment for any patient, because thanks to the procedures performed during the examination, doctors do not just discover a dangerous tumor. They collect all the information about the patient’s health status and identify tissues affected by the disease, so that subsequent treatment is selected as accurately as possible.

You can undergo a full diagnosis and any treatment for osteosarcoma at the oncology department. We carry out all research efficiently, quickly and without queues. Our clinic employs really good specialists - candidates and doctors of science with extensive experience in the fight against dangerous tumors. Our patients do not have to wait and waste time - all procedures are carried out on the territory of the center in the shortest possible time.

As a rule, such tumors are discovered after a person develops bothersome, persistent symptoms. The examination begins with a survey about your well-being and health problems, after which an examination is carried out and a number of procedures are prescribed:

• Imaging studies. Such methods allow doctors to find out whether the suspicious area is osteosarcoma, in what part of the body it first formed, how far it has spread, whether there are signs of its recurrence, and whether treatment is working correctly: Often, when a bone tumor is suspected, the first step is a plain X-ray.
  .
• Magnetic resonance imaging (MRI
  ) creates detailed images of the body's soft tissue using powerful magnets and radio waves. The method makes it possible to examine the tumor in detail and distinguish it from infection and other types of damage. An MRI is often performed with contrast, a special substance that makes the affected tissue more visible and clear.
• Computed tomography
  produces many x-ray images that are combined by a computer into one, very detailed one.
• Positron emission tomography, PET
  . Before the procedure begins, the patient receives a small dose of radioactive sugar, which accumulates in the altered tissues. A PET scan is then performed to look for any clumps of abnormal cells throughout the body.

Treatment of synovial sarcoma

The main method of treating the tumor remains radical surgical removal. In this case, a wide ablastic excision is carried out, capturing healthy tissue around the neoplasm for at least 2-4 cm. With extensive lesions, it is often necessary to resort to disarticulation and amputation of the limbs. With the expansion of chemotherapy, ablastic excision with partial preservation of vessels, nerves and tendons is becoming more common, especially if the tumor is located in the palm and wrist joint, and patients refuse amputation.

Radiation therapy carried out in the postoperative period shows better results in terms of reducing the risk of relapse, especially in the treatment of prognostically unfavorable monophasic synovioma. Chemotherapy is also indicated in the postoperative period, but its effectiveness is low for inoperable tumors.

Treatment of soft tissue cancer

The main method of treating cancer of the skin and underlying tissues is surgical excision of the tumor within healthy tissue. If the formation is large, additional plastic surgery is performed to improve the appearance. In some cases, it is also necessary to remove regional lymph nodes.

If the tumor is inoperable or it is necessary to reduce its size before surgery, chemotherapy is prescribed with modern drugs with minimal side effects and influence on the body. It is possible to use drugs after surgery to destroy remaining cancer cells and prevent relapses.

Targeted therapy protocols have been developed for melanoma, targeting only cancer cells with special monoclonal antibodies. Methods of immunotherapy for skin cancer are used with the introduction of drugs in courses to activate one’s own immune system to fight cancer Source: Paulson KG, Lahman MC, Chapuis AG, Brownell I Immunotherapy for skin cancer // Int Immunol. 2021 Jul 13;31(7):465-475. doi: 10.1093/intimm/dxz012.

Forecast

Several criteria are used to determine the prognosis of the disease and survival of patients with sarcoma:

1. Clinical. 10-year survival is observed in almost 90% of cases in patients under 25 years of age, and if the tumor occurs after 40 years of age, this figure drops to 25%. It is also worth assessing the size: if the primary tumor is up to 5 cm in size, then the 5-year survival rate reaches 90%; if it is more than 5 cm, then up to 40% of patients survive the 5-year mark. Unfavorable clinical factors may be male gender, deep localization of the tumor in the soft tissues, especially the lower limb.
2. Biochemical. A high risk of metastasis and relapse of synovial sarcoma may be indicated by a high level of endostatin and VEGF (vascular factors) in the blood.
3. Histological. According to a number of authors, the biphasic histological type is more favorable in terms of the course of the disease and sensitivity to radiation and chemotherapy.

At Euroonco, experienced oncologists treat synovial sarcoma. Thanks to the use of the latest equipment and modern treatment standards, in each case we manage to achieve the best possible result.

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