Fibrosarcoma is a malignant tumor of connective tissue origin. Develops in the thickness of the muscles, can be asymptomatic for a long time. It is a painless, round, dense, fine-grained knot, well delimited from the surrounding tissues. The skin above the tumor is not changed. Highly differentiated fibrosarcomas, as a rule, proceed quite favorably, low-differentiated ones can give hematogenic and lymphogenic metastases. The diagnosis is made taking into account clinical symptoms, radiography, CT, MRI, biopsy and other studies. Treatment – surgery, radiotherapy, chemotherapy.
C49.9 Malignant neoplasm of connective and soft tissues of unspecified localization
Fibrosarcoma is a malignant neoplasm that develops from immature fibrous connective tissue. It is part of the sarcoma group. It usually affects deeply located tissues (muscles, tendons, fascia). With previous traumatic injuries and exposure to ionizing radiation, it can occur in subcutaneous adipose tissue. Until recently, fibrosarcoma was considered a widespread oncological disease, however, as a result of immunohistochemical studies, it was possible to establish that a significant part of the pathological foci that were previously considered as fibrosarcomas are fibromatoses and fibrous histiocytomas.
It is rare in adults, usually develops at the age of 20 to 50 years. In young children, it is detected quite often. In the age group up to 5 years, fibrosarcomas account for about 50% of the total number of soft tissue oncological diseases. Usually the proximal parts of the extremities are affected (the lower extremities suffer more often than the upper ones), but they can also be detected in other areas of the human body. Fibrosarcoma treatment is carried out by specialists in the field of oncology and orthopedics.
The causes of fibrosarcoma have not yet been clarified. As a possible predisposing factor in children, chromosomal abnormalities are considered, aggravated by violations of embryogenesis as a result of adverse external influences. In adults, the risk of fibrosarcoma increases with previous repeated ionizing radiation (for example, during radiation therapy for another malignant neoplasm). At the same time, the time interval between receiving a high dose of ionizing radiation and the appearance of the first symptoms of fibrosarcoma can range from 4 to 10-15 years.
Among other unfavorable factors, experts indicate injuries and scarring that occur after certain soft tissue diseases. At the same time, it is assumed that traumatic injuries do not cause the development of fibrosarcoma, but stimulate the growth of an already existing tumor germ. Malignancy of benign neoplasms is considered unlikely, however, some researchers point to possible malignancy of fibroids, fibromyomas and fibroadenomas. Most fibrosarcomas are considered as spontaneous.
There are two main types of fibrosarcomas: highly differentiated and low-differentiated. Tumors consist of round or spindle-shaped cells located between collagen fibers.
- In the tissue of highly differentiated fibrosarcomas, the correct location of spindle-shaped cells and collagen fibers is revealed. Weak vascularization, a small number of mitoses and polymorphism of cells of varying degrees of severity are noted. Foci of necrosis are weakly expressed or absent. Highly differentiated fibrosarcomas tend mainly to a locally destructive course, metastasis is uncharacteristic.
- A distinctive feature of low-grade fibrosarcomas is the predominance of cells over collagen fibers. Intensive vascularization, pronounced cellular polymorphism, hyperchromatosis of the nuclei and a large number of mitoses are detected. In the fibrosarcoma tissue, large areas consisting of polygonal cells are viewed. With the progression of the oncological process, foci of necrosis develop in the area of these sites, which spread to neighboring zones and cause the collapse of the tumor. Low–grade fibrosarcomas are characterized by more aggressive growth, can affect lymph nodes and give hematogenous metastases, mainly to the lungs, less often to the bones and liver.
Both types of fibrosarcomas have a high tendency to relapse. Some experts note that the number of patients treated for a recurrence of fibrosarcoma exceeds the number of patients with newly diagnosed neoplasm. The reasons for the development of relapse are the absence of a capsule, the possibility of the existence of several tumor beginnings in one anatomical zone, a tendency to aggressive growth and insufficiently radical surgical intervention. To assess the prevalence of fibrosarcoma, the traditional four-stage classification and the TNM classification are used.
Clinical manifestations depend on the localization of the tumor and the prevalence of the process. When located deep in soft tissues, fibrosarcomas can be asymptomatic for a long time. Neoplasms become an accidental finding when conducting an examination in connection with another disease. Many patients go to the doctor for the first time only when fibrosarcoma reaches a significant size, causes deformation of the affected area or causes the development of contracture of a nearby joint. Fibrosarcomas of the proximal extremities may be detected earlier due to the development of pain syndrome caused by nerve compression or involvement of the periosteum.
The skin above the tumor is usually not changed. With fast-growing large and superficially located fibrosarcomas, thinning of the skin, a bluish tinge of the skin and an expanded network of subcutaneous veins in the neoplasm zone may be noted. On palpation, a single oval or round tumor-like formation of a dense consistency is detected. A characteristic feature of all types of sarcomas, including fibrosarcomas, is the impression of a limited node, a “false capsule” or pseudocapsule, which is a layer of fibrous tissue. With progression, the false boundaries of the tumor become less pronounced.
The degree of mobility of fibrosarcoma is determined by the prevalence of the process. Small local formations can shift (more often – in the transverse direction). When the surrounding tissues germinate, the fibrosarcoma becomes immobile. When the neoplasm is located in the intermuscular space, the nodes are well palpated during muscle relaxation, lose contours and lose mobility with muscle tension. In the initial stages, fibrosarcomas are usually painless. With compression of the nerves, there is pain during palpation. When the bone is affected, the pain becomes permanent.
In the late stages of fibrosarcoma, symptoms of general intoxication are revealed. The patient loses weight and appetite. There is an increase in temperature, anemia, increasing weakness, emotional lability, depression or subdepression.
When distant metastases appear, signs of damage to the relevant organs are observed. With metastatic bone damage, a persistent pain syndrome occurs, which is not eliminated by painkillers. With metastases to the lungs, cough, shortness of breath and hemoptysis are noted; with metastatic liver cancer, jaundice and organ enlargement are detected.
Timely diagnosis of this disease is one of the urgent problems of oncology. The long-term asymptomatic course, the imaginary inoffensiveness of fibrosarcoma and the lack of oncological alertness among general practitioners lead to the fact that the diagnosis in 70-80% of cases is made at the advanced stages of the disease. A partial solution to this problem lies in careful collection of anamnesis and increased attention to soft–tissue volumetric formations located in places typical of fibrosarcoma – in the area of the proximal extremities. Methods of examination:
- Radiography. At the stage of primary diagnosis, patients with suspected fibrosarcoma are referred for X-ray examination. According to the radiography data, an ovoid node with a homogeneous structure and fuzzy boundaries is determined. Calcification areas can be detected in the node area, with common processes, bone usuration is noted.
- Echography. To clarify the diagnosis, soft tissue ultrasound is prescribed, which allows to more accurately assess the size and structure of fibrosarcoma, as well as the level of its vascularization. During the study, a puncture or thick-needle biopsy is performed.
- Tomography. To determine the stage of the disease and obtain more complete data on the structure, size and location of fibrosarcoma, CT and MRI are prescribed, if necessary.
To detect distant metastases, chest x-ray, chest CT, ultrasound of the abdominal cavity and skeletal scintigraphy are used. To assess the general condition of the patient and make a decision on the possibility of surgical intervention, general blood and urine tests, biochemical blood analysis and other studies are prescribed (depending on the pathology detected).
Depending on the prevalence of the process, the treatment of fibrosarcoma can be radical or palliative. The goal of radical treatment is the complete destruction of malignant cells, prevention of recurrence and metastasis, as well as restoration of the function of the affected area. The main goals of palliative treatment of fibrosarcoma are considered to improve the quality and increase the patient’s life expectancy.
In the process of radical treatment, organ–preserving operations are mainly used – local, radical or sectoral resection. The minimum volume of excised visually unchanged tissues in fibrosarcoma should be at least 5-6 cm. The operation may include plastic surgery of large vessels, replacement of formed defects of bones and soft tissues. Amputations and exarticulations are required in no more than 10% of cases and are used for large common neoplasms in the decay stage.
At the II and subsequent stages of fibrosarcoma, radiation therapy is performed in the pre- and postoperative period. Intraoperative irradiation and brachytherapy may be used. At stage III, chemotherapy is additionally included in the treatment plan. At stage IV, chemotherapy drugs and symptomatic agents are prescribed.
With highly differentiated fibrosarcoma and the early stages of a low-differentiated tumor, the prognosis is quite favorable. With widespread low-grade fibrosarcomas, the five-year survival rate does not exceed 40-50%. The risk of relapse directly depends on the prevalence of the primary oncological process. All patients with fibrosarcoma within 3 years after the end of treatment should undergo a quarterly general examination, ultrasound of the affected area, ultrasound of the abdominal cavity and chest radiography. During the next 2 years, examinations are carried out every six months.