Liposarcoma

Liposarcoma is a tumor that arises from fat tissue. This tumor often occurs in the thigh, legs, behind the knee, or in the abdomen, but it can be found in other parts of the body, in the retroperitoneum; and, less often, in the head and neck area. Their primary occurrence in the skin is rare. Because a liposarcoma may grow into surrounding tissues or organs, it is considered a malignant tumor.

CT image showing a lesion that proved to be a liposarcoma

Subtypes

The World Health Organization classification of soft tissue tumors recognizes 5 types of liposarcomas: Well differentiated, which includes the adipocytic, sclerosing, and inflammatory subtypes; dedifferentiated; myxoid; round cell; and pleomorphic.

Cause

Doctors are not sure what causes liposarcoma. Mutations (changes) in genes found in fat cells may cause cells to grow uncontrollably, causing a tumor. Doctors have also found links between liposarcoma and other factors. Prior exposure to radiation or certain chemicals such as vinyl chloride (a toxic chemical used in making plastic) may cause liposarcoma in some people. In other cases, liposarcoma occurs due to hereditary conditions that are passed down among family members.

Symptoms

Some people with liposarcoma have no symptoms other than being able to feel a painless lump. People often notice these lumps after an injury, but trauma is not known to be a direct causative effect. You may notice symptoms as a lipomatous tumor grows and presses on surrounding nerves, muscles, or organs. Signs and symptoms of liposarcoma vary depending on the tumor’s location. They can include:

• Constipation
• Fatigue (extreme tiredness)
• Pain
• Trouble breathing
• Unexplained swelling
• Weakness

Additional images

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  Micrograph of a myxoid liposarcoma, H&E stain

• 

  Micrograph of a dedifferentiated liposarcoma, H&E stain

Diagnosis

The diagnosis is established by histologic examination of the tissue, i.e., biopsy or excision. Lipoblasts are often present; these are cells with an abundant clear multivacuolated cytoplasm and an eccentric darkly staining nucleus that is indented by the vacuoles.

Medical imaging

Ultrasonography may not be able to distinguish a liposarcoma from a benign lipoma, and therefore, MRI is the initial imaging of choice.

Treatment

The treatment for liposarcoma depends on the type, size, and location of the tumor. Surgery to remove the tumor is often the first treatment. When the tumor is in the abdomen, it may be difficult to remove completely, especially if the tumor is growing near important organs that cannot be removed.

If the entire tumor cannot be removed during surgery, radiation therapy may be used after surgery to kill any cancer cells that remain to reduce the chance of the tumor coming back (a recurrence).

Chemotherapy is another treatment that can kill remaining cancer cells following surgery, though it is not usually used to treat low-grade sarcomas. Sometimes radiation therapy or chemotherapy may be done prior to surgery to shrink the tumor; this may increase the chance of removing the whole tumor during surgery while limiting the impact to other organs. The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition.

• Eribulin mesylate (Brand name: Halaven)Treatment of patients with unresectable or metastatic liposarcoma who have received a prior anthracyclne-containing regimen.
• Trabectedin (Brand name: Yondelis) For the treatment of patients with unresectable or metastatic liposarcoma or leiomyosarcoma who received a prior anthracycline-containing regimen.

Prognosis

The prognosis varies depending on the site of origin, the type of cancer cell, tumor size, depth, and proximity to lymph nodes.

Five-year survival rates vary from 56 to 100% based on histological subtype.

Epidemiology

Most frequent in middle-aged and older adults (age 40 and above), liposarcomas are the second-most common of all soft-tissue sarcomas, following malignant fibrous histiocytomas. Annually, 2.5 cases occur per million population.

Liposarcoma Resources
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