Malignant tumors derived from mesenchymal tissues (including connective tissue and muscle) are called "sarcomas." It mostly occurs in the skin, subcutaneous, periosteum and both ends of long bones. For example, fibrosarcoma grows rapidly, and the tumor often has necrosis, bleeding, gray-red cut surface, uniform and thin like raw fish in the late stage of the tumor. Osteosarcoma is more common in young people, and it occurs at the ends of the long bones of the limbs, especially the lower end of the femur, the upper end of the tibia and the upper end of the humerus. Osteosarcoma develops rapidly and has a short course of disease. It begins to grow in the cortex, and can gradually develop into the bone marrow cavity, sometimes breaking through the periosteum, invading the surrounding soft tissues, and easily causing pathological fractures. Also common are leiomyoma, lymphosarcoma, synovial sarcoma and so on. Hematogenous metastasis can occur early.

Early symptoms
        Local symptoms: local pain and swelling or local red skin, hot joint effusion, pain and limitation of movement of limbs or joints, etc.
        Systemic symptoms: low fever, fatigue, physical discomfort, and dysfunction of related parts may occur.

Disease diagnosis
        It is common in adults, and usually occurs in the shoulders, neck, back, shoulder blades, buttocks, forearms, calves and knees.
        The lumps are mostly single, and a few patients are multiple. They are of different sizes, flat masses, or lobulated. The texture of the tumor is soft like cotton, and the appearance is swollen like a steamed bun. It can be flattened with force, and it can be moved without being touched by the skin. Adhesion, the skin on the surface of the tumor remains as usual, and there is no pain. It grows slowly, and it can stop growing on its own when it grows to a certain extent, and it is fixed. Another type of multiple sarcoma often occurs under the skin of the extremities, chest or abdomen, with multiple round or oval nodules. The texture is slightly harder than the general sarcoma, and it is mildly painful.