109. Sarcoma: definition, localization, basic principles of classification. Macro- and microscopic structural features, growth patterns, metastasis, outcomes, complications, clinical significance.

Sarcoma is a malignant (cancerous) tumor that develops in different types of connective tissue. There are several types of tumors: osteogenic sarcoma (bone tissue), chondrosarcoma (cartilage tissue), myosarcoma (muscles), liposarcoma (adipose tissue), synovial (the process affects joints, knees are more often affected), fibrosarcoma (mammary glands are often affected), as well as angiosarcoma (tumors of vascular walls). These tumor processes are often characterized by rapid growth, frequent relapses and distant metastasis.

Classification of the disease By origin:

a tumor growing from bone tissue: osteosarcoma, chondrosarcoma, Ewing's sarcoma;

a tumor growing from soft tissues: liposarcoma, lymphosarcoma, fibrosarcoma, Kaposi's sarcoma.

According to the degree of cell differentiation, the neoplasm can be low differentiated (slow growth, less malignant course) and highly differentiated (intensive growth, massive metastases).

Macro- and microscopic features of the structure

It has a pinkish-white color on the cut, resembling fish meat. Sarcoma has features peculiar to cancerous tumors: infiltrating growth with destruction of neighboring tissues, relapses after removal, early formation of metastases with their spread to the lungs (with sarcoma of the extremities, head, neck, trunk) and liver (with abdominal sarcoma). They are characterized by progressive, sometimes explosive, and generally faster tumor growth than in classical cancer, especially in children, which is explained by the more active growth of connective and muscle tissues in childhood, as well as frequent relapses. They occupy the second place after cancer among malignant diseases in terms of the number of deaths.

Sarcomas can originate from various types of connective tissue. However, there is a rare variant of malignant neoplasms of mixed genesis — carcinosarcoma. Thus, the following pathological pattern is characteristic of chondrosarcoma: peripheral chondrosarcoma is well detected in the form of a dense tumor adjacent to the cortical layer of bone, sometimes sprouting into the bone to different depths. It may contain foci of ossification and petrifications; a tumor of a dense-elastic consistency, in the presence of obliteration, decay or hemorrhage, is softer, has no clear restriction from neighboring tissue. When incised, it is not difficult to determine its cartilaginous character. Microscopically, the tumor sometimes resembles a chondroma, consists of immature cells with pronounced cellular atypism; often the tumor pattern looks like a microsarcoma, in which areas of cartilage tissue with poorly shaped cells containing irregularly shaped chondroblasts can be found.

Complications of soft tissue sarcoma can reach large sizes, put pressure on healthy tissues and cause pain. When sarcoma spreads to other organs, the functions of the affected organ are disrupted (for example, shortness of breath develops when sarcoma spreads to the lungs). Adverse factors affecting the outcome of treatment:

joining an infection;

the presence of a pathological fracture;

the development of anemia, thrombocytopenic syndrome, which require transfusion of blood components;

prolongation of the intervals between the administration of chemotherapy drugs;

reduction of doses of chemotherapy drugs;

failure by the patient to comply with recommendations during treatment and during dynamic monitoring.

The most severe consequence of the disease is amputation of the affected limb, leading to disability of patients. In addition, sarcoma tends to recur and metastasize.