Lipoma overlying hip region, note similarity in appearance to nearby subcutaneous fat


Lipoma is the most common type of soft tissue tumor. It is a growth of fat cells that causes a lump under the skin or sometimes within a muscle. The cause is unknown. Generally, the diagnosis is clear enough from imaging studies that biopsy is not required. Lipomas do not turn into cancers.

For most patients, no treatment is recommended. Although the tumors enlarge over time, the rate is slow enough that symptoms will not develop. However, when lipomas occur inside muscles, patients are more likely to experience discomfort and thus surgery may be recommended. Even with large lipomas, in almost all instances, these are outpatient procedures.


Venous malformation in forearm, two different MRI sequences showing fat & fluid content

Hemangioma/vascular malformation

These are not truly tumors but rather regions where the blood vessels have not developed normally. When these occur in the skin, they may be associated with a dark purple or red color. They also occur in the deep tissues and muscles. Although they are presumed to be present at birth, patients do not always become aware of them until adolescence or adulthood.

Generally, the diagnosis is clear enough from imaging studies that biopsy is not required. In the absence of symptoms, these can simply be observed. For patients experiencing pain, sometimes treatment with aspirin and applying wrap to the region during exercise is adequate. For patients whose symptoms persist with simple therapies, percutaneous venous sclerotherapy, a procedure commonly performed at Virginia Hospital Center, can provide excellent relief.


Schwanomma in arm nerve, note nerve (short arrow) exiting tumor (long arrow)


Schwanommas are benign tumors that grow from the cells that surround and protect nerves in the arms & legs. As the tumor enlarges, it can cause pain by compressing the nerve. In this case, patients experience this as occasional sharp, short lived, "electric" pain, mostly when the mass is struck even gently. Generally, the diagnosis is clear enough from imaging studies that biopsy is not required. 

When the mass is small and in the absence of symptoms, these tumors can simply be observed. However, for larger lesions or those already causing symptoms, usually surgery is recommended to remove the mass. 


Myxoma in thigh, note high fluid signal on MRI on left ("STIR" sequence) but absence of enhancement with contrast on right


Intramuscular myxomas are benign tumors that occur, as the name suggests, inside muscles. They grow slowly and rarely present with symptoms. In many cases, the diagnosis is clear enough from imaging studies that biopsy is not required. However, as they tend to continue to grow over time, surgery is usually recommended for medium sized or larger lesions. In almost all instances, these are outpatient procedures.


FIbromatosis in shoulder, notice how tumor both infiltrates into muscle (long arrow) and spreads along muscle covering (short arrow)

Fibromatosis (Extra-abdominal Desmoid Tumor)

Fibromatosis is benign tumor that arises the tissues that cover muscles, called the fascia. It can grow quickly and usually is associated with pain. As it grows into the muscle, it can extend tentacle-like along the fascia. For this reason, the tumor can return ("recur") even after surgery. When surgery is recommended, it is usually followed by radiation therapy to help prevent recurrence.

More recently, we are finding some medications which are showing promising activity against fibromatosis and thus are recommending surgery only in selected cases.


"Diffuse" PVNS in knee, notice tumor throughout knee joint as well as large amount of joint fluid (short arrow)

Pigmented Villonodular Synovitis (PVNS)

Pigmented Villonodular Synovitis (PVNS) is a benign tumor of the tissue that lines the inside of joints called the "synovium". The cause is unknown. PVNS is unrelated to "synovial sarcoma", which is a cancer. Despite the similar sounding name, there is no relation between the two disorders and, as a rule, synovial sarcoma does not occur inside joints. 

Generally, the diagnosis of PVNS is clear enough from imaging studies that biopsy is not required. It is most common in the knee. Patients typically present with several years of intermittent, uncomfortable swelling, rather than acute and painful swelling. Treatment is usually surgical removal of the joint lining. The tumor has a tendency to come back ("recur") after surgery, thus patients are followed with periodic MRI imaging for several years.