The type of soft tissue sarcoma you have tells you the type of cell that the cancer started in. Knowing this helps your doctor decide which treatment you need.
Leiomyosarcoma is the most common type of soft tissue sarcoma. In the UK around 600 cases are diagnosed every year.
Leiomyosarcomas develop from smooth muscle cells. This is the type of muscle that you do not control voluntarily. So it is called involuntary muscle.
Involuntary muscle 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.
These are sarcomas that develop from fatty tissue and can grow anywhere in the body. They usually show up as soft lumps.
In the UK around 440 people are diagnosed with liposarcoma every year.
Fibroblastic sarcomas grow from cells in fibrous tissue. The cells are called histiocytes or fibrocytes. Fibrosarcomas can grow in any part of the body. They are commonly found in the arms or legs.
Around 460 cases of fibroblastic sarcoma are diagnosed in the UK every year.
There are different types of fibroblastic sarcoma:
Undifferentiated pleomorphic sarcoma
This type used to be called malignant fibrous histiocytoma (MFH).
Dermatofibrosarcoma protuberans (DFSP)
This type 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 it can spread in a small number of people.
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.
This includes fibrosarcoma and myxofibrosarcoma.
Rhabdomyosarcomas develop from skeletal (striated) muscle cells. This is the type of muscle that you can control (voluntary muscle). Rhabdomyosarcomas can develop anywhere in the body.
In the UK around 120 people are diagnosed with rhabdomyosarcoma every year.
Types of rhabdomyosarcoma include:
- Embryonal rhabdomyosarcomas (more common in children and young people)
- Alveolar rhabdomyosarcomas (more common in younger adults)
- Pleomorphic rhabdomyosarcoma ( this is rare most common in adults)
Soft tissue Ewing's sarcomas
Ewing's sarcomas most commonly starts in a bone.
Rarely, it can start in soft tissues. Soft tissue Ewing's sarcoma are called extra-skeletal Ewing's sarcoma. Extra-skeletal means they are outside the bone. Around 40 cases are diagnosed in the UK each year.
These soft tissue tumours behave a bit differently to other types of soft tissue sarcoma. They're usually treated in the same way as Ewing's sarcoma that start in the bone.
These sarcomas are most commonly found around the knee, and they start in cells that look similar to cells in joints and tendons. They can be found anywhere in the body. Around 80 cases are diagnosed in the UK each year.
These sarcomas usually show up as hard lumps but can be present for some time before they start to grow bigger. They're more common in young adults.
Vascular sarcomas develop from cells that make up the walls of blood or lymphatic vessels. Around 145 people are diagnosed with this in the UK every year.
There are different types of vascular sarcoma:
- Angiosarcomas (starting in cells lining the walls of blood or lymphatic vessels)
- Haemangiosarcomas (starting in the blood vessels)
- Lymphangiosarcomas (starting in the lymph vessels)
- Haemangioendothelioma (starting in soft tissues or internal organs, such as the liver or lungs)
Malignant peripheral nerve sheath tumours (MPNST)
These cancers start in the cells that cover nerves. In the UK around 80 people are diagnosed with nerve sheath tumours every year.
There are different types of MPNSTs including neurofibrosarcomas and malignant schwannomas.
Nerves are covered in a fatty layer (sheath) to protect them. This layer is made up of schwann cells. Tumours that develop from schwann cells are called malignant schwannomas. Malignant means that it is cancerous.
Neurofibrosarcomas can develop in people with neurofibromatosis.
Gastrointestinal Stromal Tumours (GISTs)
A GIST is a rare type of sarcoma found in the digestive system, most often in the wall of the stomach.
Gastrointestinal means they start in the digestive system (the gastrointestinal tract). Stromal means they develop from tissues that support the connective tissues, controlling the movement of the gut.
Gastrointestinal stromal tumours can behave in a:
- non cancerous (benign) way, they tend to be relatively slow growing and less likely to come back
- cancerous (malignant ) way, they are faster growing, and more likely to come back or spread
Angiosarcoma of the heart
Tumours that affect the heart are very rare. Most tumours that start in the heart are not cancer, they are benign. About 1 in 4 (25%) are cancers. Most commonly these are soft tissue sarcomas.
Angiosarcomas are a type of soft tissue sarcoma that grow from cells that make up the walls of blood vessels.
The main treatment for angiosarcoma of the heart is surgery to completely remove the cancer. Other treatments include chemotherapy and radiotherapy.
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. It's very rare, with only around 150 cases diagnosed in the UK each year.
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.
Treatment for KS depends on the type of KS, and where in the body the cancer is.
Follicular dendritic cell sarcoma
Follicular dendritic cell sarcoma (FDC sarcoma) is a very rare type of blood cancer. It is similar to lymphoma, but doctors usually treat it as a soft tissue sarcoma.
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.