Both benign and cancerous fatty tumors can occur in the legs, but they have different identifying characteristics. Cancerous tumors, for example, are sometimes painful, while benign tumors are not. How fatty tumors are diagnosed and treated is the subject of this article.
Leg Fatty Tumors
Fatty tumors in legs come in two different types--benign and malignant. There are three different kinds of benign fat tissue tumors--lipomas, the most common; lipoblastomas, occurring in infants and young children; and hibernomas, which are like lipomas but much less common. A malignant or cancerous soft tissue tumor is called a sarcoma. There are two types: osteosarcomas, which develop from bone, and soft tissue sarcomas which can develop from fat, muscle, nerves, fibrous tissues, blood vessels or deep skin tissues. They can be found in any part of the body, but most occur in the arms or legs. Sarcomas are not common and most are called carcinomas.
Causes, Diagnosis and Treatment of Benign Fatty Tumors
A lipoma is a slow-growing, fatty lump usually situated between your skin and muscle layer. It moves easily with finger pressure, is doughy to the touch and generally not tender. Lipomas can become painful if they grow and press on nerves. Most are detected during middle age. The exact cause of lipomas is not known, but they do tend to run in families, indicating perhaps a genetic predisposition. Diagnosis of this type tumor is usually done with a physical exam or a tissue sample (biopsy) for lab findings. Sometimes an ultrasound or MRI or CT scan is used if the tumor is large, has unusual features or seems to go deeper than the fatty tissue. In a small number of cases the lipoma is actually a form of cancer called a liposarcoma, but these are usually very painful. There is usually no treatment for a lipoma unless it bothers you, is painful or starts to grow. Surgical removal is the most common form of treatment. Steroid injections will shrink the tumor but usually doesn't eliminate it. Liposuction uses a needle and syringe to remove the lump, but it is difficult to remove the entire lipoma with this method.
Causes, Diagnosis and Treatment of Cancerous Fatty Tumors
Soft tissue sarcomas are cancerous tumors that originate in the soft tissues of your body. Soft tissues support, surround and connect with other body structures and include muscle, fat, blood vessels, nerves, tendons and synovial tissues. They are not common, with only about 10,000 diagnosed each year in the U.S. There are various types of sarcomas but they have similar symptoms and are treated in similar ways. Liposarcomas are malignant tumors of fat tissue. Although they can occur anywhere in the body, they are most often found in the thigh, behind the knee and inside the back of the abdomen. They mainly occur in adults between 50 and 65 years old. The cause of most of them is unknown except for Kaposi's sarcoma. This particular tumor occurs in people with defective immune systems and is caused by human herpes virus 8, or HHV8. Some sarcomas may be hereditary. If your doctor suspects a sarcoma, he will take a medical history, examine you, and possibly biopsy the tumor, either with a needle or surgically. Tests such as X-rays or CT scans, ultrasound, MRI or PET scans may be done to evaluate the situation. Surgery is the most common treatment for sarcomas, and radiation and/or chemotherapy may be used, depending on whether there is lymph node involvement. At one time, amputation of the limb or leg was common, but with advances in treatment now it is not usually necessary.