There are many kinds of lumps in the body’s soft tissues. Most lumps are not cancerous. Such noncancerous lumps include lipomas (benign fat collections), cysts (fluid-filled sacs), and hemangiomas (large collections of abnormal blood vessels).
When lumps in the body’s soft tissues are found to be cancerous, they may be called soft tissue sarcomas. These are some common soft tissue sarcomas:
Spindle cell sarcomas. These cancers look like the fibrous tissue of tendons and ligaments. They are usually found in the leg, arm, or the torso (the area between the shoulders and hips).
Liposarcomas. These cancer cells look like fat cells. Although they can be found anywhere in the body, they usually start in the abdomen or thighs.
Synovial sarcomas. This is cancer of the synovial tissue. Synovial tissue surrounds joints, and includes tendons and bursae. Bursae are the fluid-filled, cushioning sacs found between tendons, ligaments, and bones.
Leiomyosarcomas. These cancer cells look like smooth muscle cells. They are often found in the abdomen and uterus, but are also found in the leg and arm muscles.
Malignant peripheral nerve sheath tumor. This cancer is also known as neurofibrosarcoma or malignant schwannoma. It is cancer of the cells that wrap around nerves. This tumor is rare, but may be seen in people with other genetic problems, such as neurofibromatosis.
Gastrointestinal stromal tumors. These can occur anywhere along the length of the digestive tract.
Ewing sarcoma. This cancer is closely related to another kind of tumor known as a small blue cell tumor or a peripheral neuroectodermal tumor. Ewing sarcoma is a tumor of young cells. It can start in almost any tissue of the body, including soft tissue and bone. This type of tumor is more common in children.