Synovial sarcoma is a malignant tumor associated with atypical transformation and proliferation of cells of the synovial membrane of joints, mucous bags and tendon sheaths. The most typical lesion of the lower extremities. Tumor metastasis occurs mainly by lymphogenic pathway. To diagnose, X-ray and angiographic examination of the lesion area, computed tomography, radioisotope scanning, biopsy, examination of lymph nodes and internal organs for the presence of metastases are performed. Treatment of synovial sarcoma consists in a combination of radiation therapy with radical removal of the tumor. Chemotherapy may be used as palliative measures.
Meaning
Synovial sarcoma is one of the most common malignant neoplasms of soft tissues. According to some data, in this group of tumors, disease occupies 32.7%. On the incision, the malignant synovial sarcoma looks like fish meat (white color). It can have many cracks and cysts, areas of necrosis and hemorrhages. Cystic cavities and crevices are often filled with mucous contents similar to synovial fluid. The cystic structure gives it a soft consistency. In the case of calcification of the tumor, it becomes hard to the touch.
The most common malignant sform is observed among the age group from 15 to 20 years. It is very rare in people over the age of 50. Women and men get sick with the same frequency. Disease sarcoma of the joints is observed in 40% of cases of malignant synoviomas, mainly the knee and ankle joints are affected. Synovial sarcoma of the mucous bags accounts for 40% of all cases of the disease, and synovial sarcoma of the tendon vaginas — 20%.
Causes
The immediate cause of atypical degeneration of synovial cells with the development of synovial sarcoma is not yet known. Among the factors that can provoke the appearance of a tumor, there is a genetically determined predisposition, exposure to carcinogens and ionizing radiation, immunosuppressive treatment in patients with cancer or organ transplantation.
Classification
To date, clinical rheumatology uses several classifications of malignant sarcoma based on various characteristics of the tumor.
According to the WHO classification, there are 2 types of malignant synoviomas:
- A two-phase synovial sarcoma contains cells with pronounced synovial differentiation; it is distinguished by the presence of cavities similar to synovial ones and spindle-shaped cells resembling the structure of fibrosarcoma. Has a more favorable prognosis.
- Single-phase synovial sarcoma has weakly expressed synovial differentiation, which makes it difficult to diagnose. It is mainly represented by light cells of large size and spindle-shaped cells.
According to the tissue structure of the tumor , the following types are distinguished:
- Fibrous — consists of fibers that resemble elements of fibrosarcoma in their structure.
- Cellularic — formed mainly by glandular tissue with cysts and papillomatous outgrowths.
Depending on the cellular structure, there are 6 forms of synovial sarcoma: giant cell, fibrous, histoid, alveolar, adenomatous and mixed.
Symptoms
The clinical picture is characterized by the occurrence of pain in the area of the affected joint or soft tissues. The pain syndrome is less pronounced if the tumor has a soft consistency. However, it increases as the synovial sarcoma grows and destroys the underlying tissues, including bone. Pain is accompanied by limited movement in the joint or the entire limb. When probing the site of soreness, a tumor formation of various sizes (from 2 to 20 cm) is detected, without clearly palpable boundaries, which may have a dense or soft consistency. The most common localization of synovial sarcoma is joints or soft tissues of the lower extremities. Lesions of the upper extremities occur in about 12% of cases.
The clinical course is accompanied by a violation of the general condition of the patient: increased body temperature, decreased appetite, weight loss, general malaise, increased fatigue. When the tumor metastases to the regional lymph nodes, their enlargement and compaction are noted. Distant metastases of synovial sarcoma are most often observed in the bones and lungs, much less often in the abdominal organs, skin and other structures.
Diagnostics
Synovial sarcoma recognition is not an easy task for a rheumatologist and oncologist. Therefore, all possible research methods are used for its diagnosis: radiography, CT and angiography of the affected area, radioisotope examination, biopsy of the formation with a thorough study of its cytological and histological structure.
X-ray examination and computed tomography reveal signs of tumor-like formation, often with areas of calcification located in its central part. In most cases, destructive changes of the adjacent bone of varying severity are noted. During angiography of the affected area in the area of synovial sarcoma, a pathological proliferation of blood vessels is observed.
Radioisotope scanning is performed with strontium. Its active accumulation in the area of synovial sarcoma makes it possible to determine the localization and approximate boundaries of tumor germination.
The most reliable diagnostic study of synovial sarcoma is a biopsy of the formation. During the histological examination of the obtained material, much attention is paid to the presence of cysts and slit-like spaces in it, which are a sign of synovial differentiation. This feature allows you to verify the synovial sarcoma and to some extent determine its prognosis.
Detection of regional synovial sarcoma metastases is performed by puncture of the lymph node. To diagnose distant metastasis, lung x-ray, skeletal scintigraphy, MSCT or abdominal ultrasound is performed. Differential diagnosis of synovial sarcoma is performed with alveolar sarcoma, mesothelioma, fibrosarcoma, hemangioendothelioma, epithelioid and light cell sarcomas.
Treatment and prognosis
The main way to treat malignant synovioma is its radical removal. The operation is performed with the capture of healthy tissues by 2-4 cm and careful observance of the rules of ablasty. The large size of the tumor may require resection of significant areas of soft tissue and bone, complete removal of the joint and regional lymph nodes, in some cases — amputation of the limb. To restore the function of the limb after the removal of the joint, it is possible to perform its prosthetics or plastic surgery.
Radiation therapy is performed before and after removal of this disease. In the first case, it allows you to slow down the intensive growth of synovial sarcoma and even achieve a reduction in its size. In the postoperative period, it is aimed at preventing tumor recurrence. Radiation therapy of synovial sarcoma is carried out in several courses.
Chemotherapy is most often used as a palliative method of treatment when diagnosing the disease at late stages and in the presence of metastasis. It can be performed as a preoperative therapy by intra-arterial infusions of anthracyclines and other cytostatic drugs.
The tendency to aggressive growth and metastasis makes the prognosis of malignant synovioma disappointing. Relapses of the tumor after its removal occur in more than 25% of cases. The five—year survival rate is only 20-40%, and the ten-year survival rate is less than 10%.