Soft Tissue Sarcomas & Subtypes

This is basic information about soft tissue sarcoma and the parts of the body it may affect.

About Soft Tissue Sarcomas

Soft-tissue sarcomas (STS) are a group of cancers that begin in the connective tissues that support and connect the body, including:

  • Blood vessels
  • Fat cells
  • Lining of joints
  • Lymph vessels
  • Muscle
  • Nerves
  • Tendons

As a result, soft tissue sarcoma can occur almost anywhere in the body. When a soft tissue sarcoma begins and is small, it can go unnoticed because it usually does not cause problems, such as pain. However, as a soft tissue sarcoma grows, it can cause pain or interfere with the body’s normal functions.

Not all sarcomas are the same. Because there are more than 50 different types of soft tissue sarcomas and each has a different natural history—meaning where they start, how they affect the body, how fast they grow, and how they respond to treatment—it is more accurate to describe them as a family of related diseases rather than as a single disease.

Specific types of sarcoma are often named according to the normal tissue cells they most closely resemble, as listed below. This is different from most other types of cancer, which usually are named for the part of the body where the cancer began. Some sarcomas do not look like any type of normal tissue and are thought to come from stem cells or other primitive cells. Stem cells are special cells that can mature into specific tissues or organs.

The list on this page describes several common types of soft tissue sarcoma and related connective tissue tumors.

 

Reference: the Cancer.Net Editorial Board, 04/2020

Subtypes of Soft Tissue Sarcoma:

Alveolar Soft-Part Sarcoma

This type of sarcoma is extremely rare and typically develops in the thigh or buttock of patients in their twenties. Alveolar soft-part sarcoma can metastasize very early to other sites of the body including the lungs, chest cavity, liver, bone, and occasionally the brain. Despite its early metastasis, people with this diagnosis can live for 10-20 years or more after diagnosis. This form of sarcoma can be resistant to standard chemotherapy.

Reference: SARC

Angiosarcoma

Angiosarcoma is an extremely rare and aggressive sarcoma in which the inner lining of blood or lymphatic vessels (endothelial cells) grow uncontrollably, creating more blood vessels that combine to form a tumor. This sarcoma can occur anywhere in the body and has a high rate of metastasis.

Reference: Angiosarcoma Awareness & SARC 

Atypical Fibroxanthoma

Atypical fibroxanthoma shows features of both fibroblasts and cells that retain fat (xanthomas). This sarcoma is primarily treated with surgery, though radiation may be used to prevent tumor recurrence. Atypical fibroxanthoma tumors very rarely metastasize.

Reference:  SARC 

Clear Cell Sarcoma

Formerly called Melanoma of soft parts, Clear cell sarcoma appears to be biologically related to Alveolar soft-part sarcoma. Clear cell sarcoma is defined by features of both sarcoma and melanoma, including the ability to travel to lymph nodes (typical of melanoma) and to the lungs (more common of sarcomas). Surgery and radiation of the primary tumor site are typical treatments for this type of sarcoma.

Reference:  SARC 

Dermatofibrosarcoma Protuberans (DFSP)

This tumor typically arises in the deeper layer of the skin (dermis). DFSP tumors often grow slowly but tend to recur after excision. They rarely travel to the lungs and other parts of the body. Treatment for this type of sarcoma typically involves surgery to remove the tumor. Radiotherapy may be used if the tumor is not fully removed by surgery.

Reference:  SARC 

Desmoplastic Small Round-Cell Tumor (DSRCT)

Desmoplastic small round cell sarcoma (DSRCT) is an aggressive and malignant sarcoma that typically starts and travels in the abdominal cavity or pelvic area long before it is clinically recognized in the majority of patients. Patients may present symptoms such as abdominal pain, constipation, or weight loss. This tumor is identified by the EWS-WT1 fusion protein, and may also co-express epithelial, neuronal, and mesenchymal markers. DSRCT may also metastazie to other parts of the body including the liver, lung, or space between the lungs (mediastinum). DSRCT often occurs in adolescents and young adults.

Reference:  Liddy Shriver Sarcoma Initiative & SARC 

Epithelioid Sarcoma

Epithelioid sarcoma often affects the extremities (arms and legs) and starts as a painless, slow-growing mass. This type of sarcoma has a high rate of metastasis, tending to travel early to other sites of the body. Epitheliod sarcoma often affects younger people more commonly than older people. Unlike other sarcomas, epithelioid sarcoma may also travel to lymph nodes.

Reference:  Liddy Shriver Sarcoma Initiative & SARC 

(Extraskeletal) Myxoid Chondrosarcoma

This type of sarcoma is a form of chondrosarcoma that shows a wide variety of histological features and typically develops in people from 20 to 40 years of age. It grows relatively slowly but has a high risk of recurrence elsewhere in the body—particularly the lungs. Extraskeletal Myxoid Chondrosarcoma typically does not respond well to standard chemotherapy drugs.

Reference: SARC 

Extraskeletal Osteosarcoma

This type of sarcoma is similar to its counterpart in the bone, but this form arises in soft tissue. Like other osteogenic sarcomas, it typically arises in older adults.  Extraskeletal osteosarcoma is fast-growing and usually occurs in the thigh, buttock, shoulder, or trunk (chest and abdomen). Recurrences after treatment are common, as is metastasis.

Reference: National Cancer Institute & SARC 

Extrarenal Rhabdoid Tumor

This type of sarcoma is very aggressive and most often occurs during childhood. Affecting the kidneys and other structures in the abdomen, Extrarenal Rhabdoid Tumors have a high risk of early metastisis—spreading to the liver, lung, and other sites.

Reference: SARC 

Fibrosarcoma

Fibrosarcomas are malignant tumors that originate in the connective fibrous tissue found at the ends of bones of the extremities and then spread to other surrounding soft tissues. Fibrosarcomas arise from fibroblasts or their precursors and form a group of tumors that are often difficult to diagnose correctly. These tumors most often affect the extremities and trunk (chest and abdomen) and can metastasize to the lungs. In the Infantile or Congenital form of fibrosarcoma, tumors present as rapidly growing masses at birth or shortly after. This form of fibrosarcoma tends to be more benign than Fibrosarcoma in older children. Adult form fibrosarcoma often occurs in children and adolescents and is more aggressive than the infantile form, generally involving more complex treatments.

An “inflammatory” version of fibrosarcoma also exists, appearing to have white blood cells throughout the tumor. Inflammatory myofibroblastic tumors are similar to the inflammatory forms of fibrosarcoma in that both have features of connective tissue cells (fibroblasts) and muscle.

Reference: Dana-Farber Cancer Institute & SARC 

Gastrointestinal Stromal Tumor (GIST)

GIST is a common type of sarcoma that develops in the gastrointestinal (GI) tract. Most GISTs are found in the stomach and small intestine, but may occur anywhere along the GI tract including the colon/rectum and the esophagus. A GIST often arises when there are specific DNA changes in specialized nerve cells that are located in the walls of the digestive system and regulate digestive processes. These tumors most often present with non-specific symptoms, including abdominal pain, feeling full, bleeding, or intestinal obstruction. GISTs have the potential to metastasize. They are usually treated with surgery, though chemotherapy is the next line of treatment if cancer has spread.

Reference: Mayo Clinic, National Organization for Rare Disorders, SARC & Sarcoma UK

Kaposi Sarcoma

Kaposi Sarcoma (KS) develops from abnormal cells that line lymph or blood vessels, causing skin lesions (purplish, reddish, blue, dark brown, or black) on the legs or face. This type of sarcoma typically presents as tumors on the skin or on mucosal surfaces, such as inside the mouth. These tumors may also develop in other parts of the body including the lymph nodes, lungs, or digestive tracts. Kaposi sarcoma is caused by infection with the Kaposi sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV8). This sarcoma is classified into the following four types based on the populations in which it develops: classic (middle-aged or elder people), endemic (often described in Sub-Saharan indigenous Africans), iatrogenic (associated with immunosuppressive drug therapy), and AIDS-associated (epidemic KS). Kaposi sarcoma tumors have a high recurrence rate, often traveling to the liver, bone, lung, and other sites. Treatment options for KS may include local therapy, radiation therapy, chemotherapy, and immunotherapy.

Reference: Liddy Shriver Sarcoma Initiative & SARC

Leiomyosarcoma

Leiomyosarcoma is an aggressive sarcoma that may occur anywhere in the body including the extremities, small intestine, stomach, and uterus. The most typical site of involvement of leiomyosarcoma is the retroperitoneum. Leiomyosarcoma is derived from smooth muscle cells and often presents as an enlarging, painless mass. This is one of the most common types of sarcoma, affecting adults and particularly women.

Reference: Liddy Shriver Sarcoma Initiative & SARC

Liposarcoma

Liposarcomas resemble fat cells under a microscope and are a common type of sarcoma. There are three families of liposarcoma: well-differentiated and/or dedifferentiated, myxoid and/or round cell, and pleomorphic. Each has its own set of characteristics and behaviors.

Myxoid and/or Round-Cell Liposarcoma
These types are the second-most common family of liposarcomas. Both forms carry the same translocations (abnormal joining) between chromosomes 12 and 16. These tumors typically occur in the leg, with a high risk of recurring in other soft tissue sites or bones such as the spine and pelvis. Myxoid liposarcoma is an intermediate to high grade tumor with cells that look abnormal under the microscope.

Pleomorphic Liposarcoma
This type of liposarcoma is the least common and is a high-grade tumor with cells that look very different from normal cells. Pleomorphic liposarcoma tends to affect the extremities, is often more aggressive, and can spread to other sites of the body including the lungs and other soft tissues.

Well-Differentiated and/or Dedifferentiated Liposarcoma 
These types of liposarcomas typically occur in the abdominal cavity or extremities, appearing as large, painless masses. Well-differentiated liposarcoma is considered to be the less aggressive form of this tumor, usually starting as a low-grade tumor with cells that tend to grow and change slowly. Dedifferentiated liposarcoma occurs when a low-grade tumor changes and is considered to be more aggressive.

Reference: Liddy Shriver Sarcoma Initiative & SARC

Malignant Peripheral Nerve Sheath Tumors (MPNST)

MPNST is a rare sarcoma cancer of the cells that form the sheath that covers and protects peripheral nerves. MPNST can occur in people who have a familial disposition to forming benign versions of these tumors, called neurofibromas or schwannomas. This cancer grows in the soft tissues of the body, such as muscle, fat, tendon, ligaments, lymph and blood vessels, and nerves. It often grows quickly and metastasizes. MPNST is most common in young adults and middle-aged adults.

Reference: National Cancer Institute & SARC

Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is a rare sarcoma that arises from a normal skeletal muscle cell. Common sites of RMS are the head and neck, urinary and reproductive organs, the extremities, and the trunk (chest and abdomen). This type of sarcoma may travel to lymph nodes and can metastasize to the lungs and other parts of the body. Rhabdomyosarcoma typically affects children and, though uncommon, it may also occur in adults.  Treatment for this type of sarcoma typically involves surgery, radiation, and chemotherapy.

Reference: American Cancer Society, Liddy Shriver Sarcoma Institute & SARC

Synovial Sarcoma

Synovial sarcoma, despite its name, is not related to the synovial tissues that are part of the joints. This type of sarcoma often presents as a slow-growing mass that most commonly occurs in the extremities but can also appear in any part of the body. Synovial sarcoma is a high-grade tumor, spreading to distant sites of the body in many cases including the lungs.

Reference: Liddy Shriver Sarcoma Institute & SARC

Undifferentiated Pleomorphic Sarcoma (UPS)

Formerly called Malignant Fibrous Histiocytoma (MFH), Undifferentiated Pleomorphic Sarcoma (UPS) is a malignant neoplasm of uncertain origin that arises in both soft tissue and bone. This type of sarcoma has a broad range of histologic appearances and typically presents in older patients of approximately 50 to 70 years of age. UPS can develop in any part of the body but is most commonly seen in the upper extremities and retroperitoneum. Patients often complain of a mass or lump that has grown over a short period of time and it’s not uncommon for this to occur in an area affected by trauma. Surgical excision is most often supplemented with adjuvant radiation therapy for this type of sarcoma.

Reference: Liddy Shriver Sarcoma Institute & SARC

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