Overview

Soft tissue sarcoma is a rare type of cancer that begins in the tissues that connect, support and surround other body structures. This includes muscle, fat, blood vessels, nerves, tendons and the lining of your joints.

More than 50 subtypes of soft tissue sarcoma exist. Some types are more likely to affect children, while others affect mostly adults. These tumors can be difficult to diagnose because they may be mistaken for many other types of growths.

Soft tissue sarcoma can occur anywhere in your body, but the most common types occur in the arms and legs, and in the abdomen. Surgical removal is the most common treatment, although radiation and chemotherapy also may be recommended — depending on the size, type, location and aggressiveness of the tumor.

Symptoms

A soft tissue sarcoma may not cause any signs and symptoms in its early stages. As the tumor grows, it may cause:

  • A noticeable lump or swelling
  • Pain, if a tumor presses on nerves or muscles

When to see a doctor

Make an appointment with your doctor if you have:

  • A lump that is increasing in size or becomes painful
  • A lump of any size that's located deep within a muscle
  • Recurrence of a lump that's been removed

Causes

In most cases, it's not clear what causes soft tissue sarcoma.

In general, cancer occurs when cells develop errors (mutations) in their DNA. The errors make cells grow and divide out of control. The accumulating abnormal cells form a tumor that can grow to invade nearby structures and the abnormal cells can spread to other parts of the body.

The type of cell that develops the genetic mutation determines what type of soft tissue sarcoma you have. For example, angiosarcoma begins in the lining of blood vessels, while liposarcoma arises from fat cells. Some types of soft tissue sarcoma include:

  • Angiosarcoma
  • Dermatofibrosarcoma protuberans
  • Epithelioid sarcoma
  • Gastrointestinal stromal tumor (GIST)
  • Kaposi's sarcoma
  • Leiomyosarcoma
  • Liposarcoma
  • Malignant peripheral nerve sheath tumor
  • Myxofibrosarcoma
  • Rhabdomyosarcoma
  • Solitary fibrous tumor
  • Synovial sarcoma
  • Undifferentiated (pleomorphic sarcoma)

Risk factors

Factors that may increase your risk of sarcoma include:

  • Inherited syndromes. A risk of soft tissue sarcoma can be inherited from your parents. Genetic syndromes that increase your risk include hereditary retinoblastoma, Li-Fraumeni syndrome, familial adenomatous polyposis, neurofibromatosis, tuberous sclerosis and Werner syndrome.
  • Chemical exposure. Being exposed to certain chemicals, such as herbicides, arsenic and dioxin, may increase the risk of soft tissue sarcomas.
  • Radiation exposure. Previous radiation treatment for other cancers can increase the risk of soft tissue sarcomas.