Liposarcoma

A liposarcoma is a cancer made up of fat cells, usually as a soft tissue sarcoma deep in the abdomen (belly), buttocks, arms, or legs. Liposarcomas may also occur as a rare esophageal cancer.

Liposarcomas mostly affect middle-aged adults, from 50 to 65. Many of these tumors are low grade and grow slowly. Some forms may act more aggressively. These cancers sometimes return after treatment and can metastasize (spread). When they do spread, it may be to the lungs, the liver, and other soft tissue.

Liposarcomas are the second most common soft tissue sarcoma, accounting for 20 percent of cases, though only 1,700 are diagnosed in the U.S. each year.

The Sarcoma Program at Penn Medicine's Abramson Cancer Center includes specialists with extensive experience diagnosing and treating liposarcoma. Our team works closely across multiple specialties to accurately identify these rare tumors and recommend the most effective treatment approach.

Liposarcoma versus lipoma

Another kind of fatty tumor—benign (noncancerous) lipoma—is much more common than liposarcoma. For every 1,000 people, two will develop a lipoma, on average. These tumors usually do not cause any symptoms and generally do not need to be removed. If you develop an unknown fatty lump, a doctor starts by comparing the differences between liposarcoma and lipoma:

• Consistency: Lipomas feel soft and rubbery, while liposarcomas may feel firm.
• Location: While they can form deeper, lipomas often grow closer to the surface of the skin. Liposarcomas tend to develop deeper in tissues.
• Size: While some are bigger, lipomas generally reach no more than 2 inches across. Liposarcomas can grow quite large, particularly in the back half of the belly (the retroperitoneum).
• Sensation: Neither lipomas nor liposarcomas generally cause pain.

We categorize liposarcoma based on where tumors form and how aggressively they act.

Liposarcoma types include:

• Well-differentiated liposarcoma: The most common liposarcoma, these tumors feature clearly defined cells that look a lot like normal cells. These cancers rarely spread but do often return after surgical treatment. They’re found in the retroperitoneum (back half of the belly) and the esophagus. In the arms and legs, a similar but benign tumor called an atypical lipoma can develop. In 2 percent of cases, these lipomas can turn into liposarcoma.
• Myxoid liposarcoma: Among liposarcomas, these tumors are also relatively common, especially in adults ages 35 to 55. Myxoid liposarcoma is found most often in the thighs. It can also form in the chest wall, pelvis, arms, and other parts of the legs.
• Round cell liposarcoma: Named after the shape of its cells, round cell liposarcoma is the more aggressive version of myxoid liposarcoma and occurs in the same locations. It can spread to other areas of the body, including the lungs, abdomen, and spine.
• Dedifferentiated liposarcoma: This less common form of liposarcoma is found in the belly, arms, and legs. Its cells appear dedifferentiated, meaning that they are in a less mature form. Dedifferentiated liposarcoma can act more aggressively at times. For example, it returns more often after treatment when found in the belly. Still, dedifferentiated liposarcoma spreads to other areas of the body less commonly than other aggressive liposarcomas.
• Pleomorphic liposarcoma: The rarest liposarcoma, these tumors have cells that take on a range of shapes and sizes. Found mainly in the arms and legs, these sarcomas are particularly aggressive, with the ability to spread to distant locations, particularly the lungs.

When they first form, liposarcomas often don’t cause any symptoms and frequently go unnoticed. They may eventually grow large enough to push other tissue aside and cause symptoms. The liposarcoma symptoms you may experience depend on the size of the tumor and where it forms:

• Abdominal symptoms: You may experience constipation, feeling full sooner than usual when eating, nausea, pain, swelling, unintended weight loss, or vomiting.
• Arm or leg symptoms: You will most commonly notice a growing lump but generally no pain or physical limitations.
• Esophageal symptoms: You may experience trouble swallowing or unintended weight loss.

The exact causes of liposarcoma aren’t currently known. Some factors, however, may increase your risk of developing one:

• Chemical exposure: Some evidence suggests that exposure to workplace chemicals such as vinyl chloride can cause a liposarcoma to eventually form.
• Family genetics: Genetic changes inherited from parents can cause syndromes that increase the risk for a range of health conditions, including sarcomas and other cancers. Both hereditary retinoblastoma—a cause of eye cancer—and Li–Fraumeni syndrome (LFS) have ties to liposarcoma.
• Lipomas: Most benign lipomas don’t turn cancerous. In 2 percent of cases, a specific kind of tumor called an atypical lipoma may become a liposarcoma.
• Previous radiation therapy: Receiving radiation therapy can cause a liposarcoma to form years later.

Treating liposarcoma well takes more than one specialist. It takes a team with the combined experience to recognize its many forms and the skill to act on what they find. At Penn Medicine, specialists in surgical oncology, orthopaedic oncology, pathology, radiology, medical oncology, and radiation oncology evaluate every case together.

Our research involvement keeps that expertise current. Through clinical trials and partnerships with leading organizations like the Sarcoma Alliance for Research through Collaboration (SARC), we’re not just treating liposarcoma, we’re working to change how it’s treated.