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Types of soft tissue sarcoma

Soft tissue sarcomas can develop in any of the soft connective tissues of the body. So there are many different types including

  • Fibrosarcomas that grow from fibrous body tissues
  • Leiomyosarcomas and rhabdomyosarcomas that start in muscle cells
  • Liposarcomas of fatty tissue
  • Synovial sarcomas, which start near the joints of arms and legs
  • Angiosarcomas that start in the walls of blood or lymphatic vessels
  • MPNST – malignant peripheral nerve sheath tumours (PNSTs) that develop from the soft tissues that surround nerves
  • GIST – gastrointestinal stromal sarcoma that develops in the digestive system
  • Kaposi’s sarcoma of the skin
  • Soft tissue Ewing's sarcoma (extra-skeletal Ewing's sarcoma)

 

CR PDF Icon You can view and print the quick guides for all the pages in the About soft tissue sarcoma section.

 

 

Fibrosarcomas

Fibrosarcomas grow from cells in fibrous tissue. The cells are called histiocytes or fibrocytes.  Fibrosarcomas can grow in any part of the body. But they are most commonly found in the arms or legs.

There are different types of fibrosarcoma. One type is called undifferentiated pleomorphic sarcoma. This type used to be called malignant fibrous histiocytoma (MFH). MFH used to be one of the most common types of soft tissue sarcoma. But doctors don't use this term very often now. Most of the tumours that used to be called MFH are now more accurately diagnosed as other types of sarcoma. The small number that would still be called MFH are now known as undifferentiated pleomorphic sarcoma.

Dermatofibrosarcoma protuberans (DFSP) is another type of fibrosarcoma. It is extremely rare and starts in the skin. It occurs most often in adults in their 30s. It usually behaves like a non cancerous (benign) tumour and does not spread but in 2 to 5% of cases it can spread. There is a small risk that DFSP can change and develop into a different type of fibrosarcoma which behaves more like a cancererous tumour. This is called malignant transformation. 

 

Leiomyosarcomas and rhabdomyosarcomas

These sarcomas start in muscle cells. Leiomyosarcomas develop from smooth muscle cells. This is the type of muscle that you do not control voluntarily. So it is called involuntary muscle. It forms the walls of the womb, stomach, intestine and blood vessels. Rarely, leiomyosarcoma starts in the muscle of the womb and is called uterine sarcoma.

Rhabdomyosarcomas develop from skeletal (striated) muscle cells. This is the type of muscle that you can control. Rhabdomyosarcomas are found most often in the arms and legs. 

There are two main types of rhabdomyosarcoma – embryonal and alveolar. Embryonal rhabdomyosarcomas tend to occur more commonly in children and young people. Alveolar rhabdomyosarcomas tend to occur more often in younger adults. There is a third type called pleomorphic rhabdomyosarcoma. This is rare and tends to occur in adults.

 

Liposarcomas

These are sarcomas that develop from fatty tissue and can grow anywhere in the body. They usually show up as soft lumps.

 

Synovial sarcomas

These sarcomas are most commonly found around the knee, and they start in cells close to joints and tendons. They can be found anywhere in the body. These sarcomas usually show up as hard lumps but can be present for some time before they start to grow bigger. They are more common in young adults.

 

Angiosarcomas

Angiosarcomas start from the cells that make up the walls of blood or lymphatic vessels. If they start in the blood vessels they are called haemangiosarcomas. If they start in the lymph vessels they are called lymphangiosarcomas.

 

Malignant peripheral nerve sheath tumours

These are cancers of the cells that cover nerves. There are different types of MPNSTs including neurofibrosarcomas and malignant schwannomas. Schwannomas develop from the cells that form the fatty sheath which covers nerves. These cells are called schwann cells.

 

Gastrointestinal Stromal Tumours (GISTs)

Gastrointestinal stromal tumours can behave in a non cancerous (benign) way. Or they can behave in a cancerous (malignant) way.  Generally, a tumour that behaves in a benign way tends to be relatively slow growing and less likely to come back. A tumour that behaves in a malignant way is faster growing, and is more likely to come back or spread.

You may hear GIST that behaves in a cancerous way called GI stromal sarcoma. Generally speaking, the larger the GIST, the more likely it is to behave like cancer. These tumours develop from the cells of the connective tissues that support the organs of the digestive system – the gastrointestinal tract. Most are found in the stomach. GIST is treated differently from other types of soft tissue sarcoma.

 

Kaposi's sarcoma

Kaposi’s sarcoma develops from cells called endothelial cells. Most cases occur in the skin but it can also develop in internal organs of the body. Coloured nodules develop on the skin, in the mouth and lymph nodes, and in organs such as the lung, liver and spleen. It is very rare, with only 155 cases diagnosed in the UK in 2007. 

Some types of Kaposi's sarcoma are known to be associated with HIV (human immunodeficiency virus) infection and AIDS (acquired immunodeficiency syndrome). It can be caused by a sexually transmitted virus called human herpes virus 8 (HHV8) or Kaposi's sarcoma herpes virus (KSHV). Other types are associated with Jewish, Italian and West African ancestry. Kaposi's sarcoma is treated differently to many soft tissue sarcomas and so is not covered in this section.

 

Soft tissue Ewings sarcomas (extra-skeletal Ewing's sarcoma)

Ewing's sarcomas occur in bone and they can also develop and grow in soft tissues. Ewing's that grow in the soft tissue are called extra-skeletal Ewing's sarcoma. Extra-skeletal means they are outside the bone. These soft tissue tumours behave a bit differently to other types of soft tissue sarcoma. They are usually treated in the same way as Ewing's sarcoma that start in the bone. You usually have chemotherapy to shrink the tumour, followed by surgery to remove it and sometimes radiotherapy after surgery. So you may find the bone tumour section more useful if you are looking for information about treatment for Ewings sarcoma in the soft tissue.

PNET stands for primitive neuroectodermal tumour. It used to describe a type of Ewings sarcoma that starts in soft tissues. But doctors don't use this term any more. All soft tissue Ewing's sarcomas are grouped together and described as extra-skeletal Ewing's sarcoma or soft tissue Ewing's sarcoma.

 

Fibromatosis

Fibromatosis is not actually a sarcoma, but we have included it here because we are sometimes asked about it. Fibromatosis is not cancer. It does not spread around the body but these tumours can spread into nearby tissues. It is also called aggressive fibromatosis or a desmoid tumour. 

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Updated: 9 February 2015