What does a sarcoma lump look like?

X-ray of a knee showing a soft tissue mass sarcoma - stock

Finding a lump or bump on any part of your body can be alarming. While the majority of these are harmless, it is always good to know when to seek medical attention.

The most common lumps and bumps that appear in soft tissues are lipomas. Made of fat cells, lipomas rarely change in size, are easy to move around and are not cancer. But, what does a lump or bump look like when it is cancer, particularly sarcoma, an aggressive kind of cancer that can spread and metastasize quickly?

A soft tissue sarcoma lump on the outside of the body can appear suddenly as a rounded mass beneath the skin, usually on your arm, leg, chest, or torso. It can be soft or firm and grows noticeably bigger in weeks and months after it is first discovered. There are about 100 distinct kinds of soft tissue sarcoma, which starts in the flexible, elastic soft tissues and deep spaces in the body, such as fat, muscle, nerves, fibrous tissues, blood vessels or deep skin tissues. Although less common, it can also begin in your bones. About four in every 100,000 people in the U.S. are diagnosed with sarcoma each year: men are diagnosed slightly more than women and African Americans have the highest incidence of soft tissue sarcoma.

“Sarcomas are very rare. There are not known causes but there are some known associations,” explains sarcoma expert John Kane, MD, Chair of Surgical Oncology at Roswell Park Comprehensive Cancer Center.

“A small subset of diagnoses is attributed to genetics. Undergoing therapeutic radiation, such as for breast cancer, is actually a risk factor, and chemical exposure to herbicides and pesticides is also known to be associated with sarcoma.”

When a lump or bump needs medical attention

Typically, cancerous lumps and bumps that develop on the outside of your body are large, hard, and painless to touch; and they cannot be moved around easily. A sarcoma lump may seem harmless at first. Because it is painless and there are usually no other early symptoms, it can be easy to dismiss.

“If you have a sarcoma mass in your thigh, you are going to notice that your thigh is getting bigger. If it’s on the surface of the skin, you may see a specific mass that is getting bigger and bigger. Eventually the skin may start to change,” Dr. Kane says.

“Anything that is continuing to grow at a reasonable rate needs to be evaluated. If you didn’t have this bump on your thigh four months ago and now you’ve got something the size of a golf ball there, which is about five centimeters, the likelihood that it might be a sarcoma starts to go up,” he adds.

Never miss another Cancer Talk blog!

Sign up to receive our weekly Cancer Talk e-newsletter.

Sign up!

Like the external lump you can see, an internal sarcoma does not usually produce symptoms in the initial stages. In the abdomen or lungs, however, it can cause nausea and vomiting, constipation, cough or shortness of breath and eventually pain, if it begins to press on nearby organs, nerves, muscles or blood vessels.

“People may notice they are not gaining weight but that their belt is getting tighter. They know something is not right,” Dr. Kane says. He adds that no matter where sarcoma develops in the body — in your arm, leg, stomach or spine — it is still considered sarcoma cancer, and is different from breast, lung and other kinds of cancer.

“What’s really important is finding an oncologist who understands sarcoma and how it behaves, no matter where it is in the body.”

Getting an accurate and timely diagnosis

A soft tissue sarcoma lump may often be mistaken by medical practitioners for a hematoma (bad bruise), abscess (inflamed bump), pulled muscle, lipoma or something else that is benign. Sarcoma in general can be difficult to diagnose, and X-rays or a standard ultrasound does not provide a definitive diagnosis.

“The average time from when a patient notices a lump and actually making the diagnosis that it is a sarcoma is about six months. Because sarcomas are so rare, many medical practitioners don’t put it on the list of possibilities. And you are not going to be able to tell on a physical exam if it’s benign or malignant,” Dr. Kane says.

He advises people who suspect a sarcoma lump to seek both CT and MRI imaging, followed by a radiologist-guided needle biopsy and other radiological tests to determine its makeup and size. Optimal treatment should be individualized according to the kind of sarcoma, its location in the body and potential for metastasis.

“Sarcoma tends to prefer spreading to the lungs over other places. Whenever we have a patient with a newly diagnosed sarcoma, part of the work up, and follow up, is to see if it has already spread to the lungs,” Dr. Kane says.

He adds that, because sarcoma is different, standard treatments — such as chemotherapy, radiation and surgery — for breast, lung, colon and other cancers may be altered. He recommends evaluation and care at a sarcoma center, like Roswell Park, with a multidisciplinary team of oncologic surgeons and radiation oncologists who specialize in the diagnosis and treatment of sarcoma tumors.

“We are a true sarcoma center. We have clinical trials open for some rare forms of sarcoma, intraoperative radiation options and regional therapy and chemo drugs with the ability to deliver treatment right to where it needs to go and may help avoid amputation,” he says. “We want to decide the best order of treatment to give patients the best chance of being cured.”