What Are the Most Common Soft Tissue Tumors?

Soft tissue sarcoma is a rare type of cancer that develops in the soft tissues, which connect and support different body structures. Cancer develops when abnormal cells begin to proliferate uncontrollably and do not attain the maturity to perform normal cellular functions.

Soft tissue sarcoma may not cause any symptoms in the initial stages but later manifest as a lump or swelling that may or may not cause pain. It can appear everywhere in the body, although it is mostly found in the thigh, shoulder, arm, pelvis, and abdomen.

Aside from the bones, soft tissue refers to all supporting tissues in the body, such as:

• Fat
• Muscle
• Nerves
• Tendons
• Lymph vessels
• Blood vessels

Liposarcoma

• Rare cancer that begins in the fat cells, responsible for up to 18% of all soft tissue sarcomas
• Can arise in any part of the body, although more than half of the cases involve the thigh, followed by the abdominal cavity
• Most affects adults ages 40 to 60, although teens can also develop liposarcoma

Undifferentiated pleomorphic sarcoma (UPS)

• Previously known as malignant fibrous histiocytoma
• Made up of many abnormal spindle-shaped cells
• Can arise anywhere in the body but most commonly in the extremities (arms and legs) or behind the abdominal organs
• Usually spreads rapidly to other regions of the body, including the lungs
• Often affects older people, with men accounting for two-thirds of all cases

Leiomyosarcoma

• A smooth muscle tumor that accounts for 5%-10% of soft tissue sarcomas
• Can be dormant for long periods of time
• May be treated with surgery, radiation therapy, and/or chemotherapy
• Linked to various organs, including the esophagus, stomach, intestine, anus, and uterus
• More common in adults than in children

Rhabdomyosarcoma

• A rare type of cancer that develops in the rhabdomyoblasts (immature embryonic mesenchymal cells) that can develop into skeletal muscles during the embryonic stage
• Usually diagnosed in children but can affect adults in rare cases
• Has good outcomes if treated early between ages 1 to 9
• Affects boys more than girls
• More likely to develop in children who inherit certain genetic disorders from their parents:
  • Neurofibromatosis type I
  • Beckwith-Wiedemann syndrome
  • Noonan syndrome

Angiosarcoma

• Rare cancer in which the cells that line the blood vessels or lymph vessels grow uncontrollably
• Occurs mostly in adults older than 50
• May present as a bruise-like lesion on the skin although it can also affect deeper structures, such as the liver
• May occur on the skin of the chest wall in women who have undergone radiation therapy for breast cancer

Fibrosarcoma

• An uncommon type of sarcoma that can develop anywhere in the body.
• More common among people in their 40s and 50s
• Usually affects men more than women 
• The cause is unclear but radiation exposure has been linked to some cases 
• Known risk factors include lymphoedema (swelling of the lymph nodes), chemical exposure, and hereditary disorders

Ewing's sarcoma

• A rare bone tumor, which may be extraosseous (occurs in the soft tissues outside of the bone)
• Mostly seen among children and teenagers although it can affect adults as well
• Can rapidly metastasize (spread) to the lungs, other bones, and bone marrow, and requires aggressive treatment

Gastrointestinal stromal tumor

• A type of soft tissue sarcoma that begins in the gut
• Most commonly affects the stomach and small bowel
• May present as nausea, vomiting, abdominal lumps, and pain
• Most commonly affects adults although it can rarely affect children

Although the exact cause of soft tissue sarcoma is unknown, certain risk factors have been identified:

• Radiation therapy: A small percentage of people who have already had radiation therapy to treat other forms of cancer are at risk of sarcoma.
• Hereditary disorders: Some uncommon, hereditary disorders can increase the probability of being diagnosed with soft tissue sarcoma.
• Chemical exposure: Some sarcomas have been related to exposure to chemicals such as vinyl chloride (used to create plastic) and some high-dose herbicides (weed killers).
• Others: Long-term lymphoedema (swelling caused by a buildup of lymph fluid) in the body, such as in the legs or arms, has been associated with angiosarcoma.

Benign or noncancerous soft tissue tumors develop from connective tissue, which includes fat, muscle, fibrous tissue, nerves, and vascular tissue. 

Benign soft tissue tumors of the musculoskeletal system are 100 times more common than their sarcomas (malignant tumors). Most benign soft tissue tumors are subcutaneous (just beneath the skin) and less than 5 cm in size.

Lipomatous (fatty) tumors, fibrous tumors, vascular tumors, and nerve sheath tumors are the most common types of benign soft tissue tumors:

Lipoma

• A benign (noncancerous) tumor composed of fat tissue
• Manifests as small, soft, rubbery lumps just beneath the skin
• Usually painless and appears on the upper back, shoulders, arms, buttocks, and upper thighs
• Can also be found in deeper tissue of the thigh, shoulder, or calf
• Can arise at any age although they are most common between the ages of 40 and 60 years
• Affects men somewhat more than women 

Elastofibroma dorsi

• A benign, rare fibroelastic tissue disorder that affects mostly women in their 40s 
• Commonly found in the subscapular area (under the shoulder blades) and may be bilateral at times
• Generally does not cause any symptoms although it may grow to cause some discomfort and pain while rotating the scapula, even at its apex

Desmoid tumor

• Most typically seen in the fibrous (connective) tissues, which connect, support, and surround other body parts and organs
• May grow rapidly and require aggressive treatment
• Can appear anywhere on the body but are more common in the arms, legs, and abdomen
• Also known as aggressive fibromatosis because it resembles fibrosarcoma, a malignant (cancerous) tumor (however, it is benign because it does not metastasize)
• Has the appearance of thick scar tissue
• Can be difficult to remove because they attach to surrounding tissues and organs

Tenosynovial giant cell tumor (TGCT)

• A rare tumor that develops in the:
  • Synovium (joint lining)
  • Tendon sheath (tissue that surrounds the tendons)
  • Bursa (a fluid-filled sac between the bones, tendons, and muscles)
• Produces thickening and overgrowth of the affected synovium, tendon sheath, or bursa
• Can develop in any joint.
• Not cancerous although they can grow and harm surrounding tissues or structures
• Can cause reduced mobility or discomfort in the affected joint and a locking or catching sensation when moving the joint
• Most commonly affects young and middle-aged people (25 to 50 years)

Hemangioma and vascular malformations

• Blood vessel growths also called birthmarks
• Typically develop within the first few weeks of life
• Commonly form as noncancerous skin growth growths, which begin as small red spots that can arise anywhere in the skin, mucous membranes, or internal organs but are mostly found in the head or neck
• Affects women three times more than men
• Most continue to grow during the first 3-5 months of life, but later they begin to decrease in size, and most of them are gone by the age of ten
• May be inherited and are commonly seen in multiple births and preterm infants with low birth weight

Neurofibroma

• A benign tumor that grows along the nerve cells
• Can be a sign of neurofibromatosis, a category of uncommon, hereditary disorders
• May be found on the skin, under the skin, or deeper in the body
• The majority do not create any medical issues, although larger neurofibromas can impact many nerves and create major medical problems
• Present from birth although it may take years for the tumors to become visible; usually become apparent during adolescence (around 25% of such adolescents acquire tumors large enough to cause major medical problems)