Soft Tissue Sarcoma

The words "soft tissue" confuse many people. Soft tissues are what hold the body together. They include muscles, tendons, blood vessels, fat, nerves, and deep skin tissues. Soft tissues do not include bones or other organs. Although body parts such as lungs, breasts, and colons are soft,  they are not considered part of the "soft tissues". 

Most soft tissue sarcomas do not cause pain. They are usually diagnosed when a patient notices a lump that is does not stop growing and brings it to the attention of her physician.  When soft tissue sarcomas occur in the inside or the back of the thigh, they may get very large before they are diagnosed.  Learn more about sarcoma basics, grading & staging here [link to Sarcoma Basics]. There are many variants of soft tissue sarcoma, Below are the most common types.


Undifferentiated sarcoma, medial thigh, brighter areas are due to hemorrhage within the tumor, often seen in high grade tumors

Undifferentiated Sarcoma (Spindle Cell Sarcoma, Malignant Fibrous Histiocytoma) 

The most common type of soft tissue sarcoma is actually one which does not demonstrate characteristics of any particular subtype, i.e. it is "undifferentiated". In the past, this type was named "malignant fibrous histiocytoma", the current name is "undifferentiated pleomorphic sarcoma".

This type is mostly found in adults and seniors and most commonly about the thighs & buttock. Like most soft tissue sarcomas, it is treated with a combination of radiation and surgery. Typically, radiation is given before surgery, unless the tumor is just under the skin. Surgery will involve removing the tumor along with a covering of normal muscle, called a "wide resection".

We believe that chemotherapy may slightly increase survival for patients with many types of soft tissue sarcoma. However, depending on their age and medical condition, it may not always be advantageous. Most of our patients will have a personalized consultation with our sarcoma medical oncology specialist Dr. Alex Spira shortly after surgery. At that time, they will discuss the role of chemotherapy for their specific condition.



Liposarcoma is a type of soft tissue sarcoma in which the cells produce varying amounts of microscopic fat. There are various sub-types of liposarcoma. One of these is called "well-differentiated liposarcoma". This is a slow growing tumor which appears somewhat similar to normal fat on MRI. In fact patients with large lipomas (benign fatty tumors) are sometimes suspected of having a well differentiated liposarcoma. 

However, an experienced musculoskeletal tumor specialist can usually differentiate between the two conditions based on physical examination and MRI. This is one of the more common referrals to our center. More importantly, well-differentiated liposarcomas do not have any metastatic potential, despite the word "sarcoma" in the name. The only treatment required is surgical removal of the tumor, without any additional muscle.

Other subtypes of liposarcoma ("myxoid", "pleomorphic", etc.) are treated similarly to undifferentiated sarcoma (see above). This means radiation followed by "wide-resection" surgery, followed by discussion about possible chemotherapy.


Synovial sarcoma in groin region, small areas of darker signal correspond to calcifications often seen with synovial sarcoma

Synovial Sarcoma

Synovial sarcoma is unusual among soft tissue sarcomas in that it commonly occurs in young adults and is more likely to be painful. Im some cases, it grows very slowly. Some patients may experience unexplained pain for months or even years before diagnosis.

The tissue that lines the inside of joints is named "synovium". But despite this, synovial sarcoma has nothing to do with joints. It received that name many years ago based on a superficial microscopic resemblance of the tissues. 

Unlike other sarcomas, synovial sarcoma is very sensitive to chemotherapy. Thus large tumors are often treated with a combination of radiation, surgery and chemotherapy. 



Leiomyosarcoma is an uncommon soft tissue sarcoma that grows from "smooth muscle" cells. These types of muscle cells are found in blood vessels and in the walls of the organs. Leiomyosarcoma of the organs is treated by different specialists.

Since blood vessels are found in all tissues, leiomyosarcomas may grow in skin, muscle and even bone. Treatment is radiation and surgery. If a large blood vessel is involved, a vascular bypass may also be needed. 


Dermatofibrosarcoma Protuberans (DFSP)

Dermatofibrosarcoma Protuberans is a slow growing sarcoma of the skin. It does not cause pain and usually appears a thickened, slightly discolored region plaque of skin that slowly enlarges. It has very little probability of spreading to the lungs.  

Because of its superficial location, it is often first biopsied by other specialists before referral. If it occurs on the face or the hands, dermatologists who perform Mohs surgery should excise it. This is a technique where thin shavings of skin are repeatedly performed until all the tumor is excised. In other parts of the body, it is usually surgically excised.



Rhabdomyosarcoma occurs mostly in children. Unlike the other types of soft tissue sarcomas, it is always treated with chemotherapy. Radiation, rather than surgery, is usually used for the original location. One subtype of rhabdomyosarcoma ("pleomorphic rhabdomyosarcoma") may rarely be found in adults. In these cases, treatment is similar to other soft tissue sarcomas, namely radiation followed by "wide-resection" surgery.