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Dedifferentiated Liposarcoma

Last updated Aug. 24, 2018

Approved by: Krish Tangella MD, MBA, FCAP


High magnification microscopic pathology image showing Dedifferentiated Liposarcoma. H&E stain.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Dedifferentiated LS

What is Dedifferentiated Liposarcoma? (Definition/Background Information)

  • Dedifferentiated Liposarcomas are slow-growing, malignant soft tissue tumors. These tumors are typically present in the retroperitoneum (abdominal cavity) followed by the limbs
  • The cause of development of these tumors is unknown, but some genetic mutations have been observed
  • The treatment involves a complete surgical excision and removal of the tumor. 20% of Dedifferentiated Liposarcomas metastasize and the prognosis depends upon several factors including the tumor location
  • A liposarcoma (LPS or LS) is a rare and malignant tumor of the fat cells. They are generally asymptomatic and can occur anywhere in the body
  • There are 4 main types of liposarcomas and these include:
    • Well-Differentiated Liposarcoma (WDLS): Approximately 45% of all types of liposarcomas are well-differentiated
    • Dedifferentiated Liposarcoma: It is a high-grade morphology tumor       
    • Myxoid Liposarcoma: This type constitute 30% of all liposarcomas
    • Pleomorphic Liposarcoma (PLS): It is the rarest type and constitute about 5% of all liposarcomas

Who gets Dedifferentiated Liposarcoma? (Age and Sex Distribution)

  • Dedifferentiated Liposarcoma is observed with a higher incidence in men, who are around 60 years old; though women may also be affected
  • There is no known ethnic or racial preference; it is observed worldwide

What are the Risk Factors for Dedifferentiated Liposarcoma? (Predisposing Factors)

  • No clear risk factors have been identified for Dedifferentiated Liposarcoma occurrence

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Dedifferentiated Liposarcoma? (Etiology)

  • The exact cause and mechanism of formation of Dedifferentiated Liposarcoma is unknown
  • It is thought to occur spontaneously due to certain genetic mutations (chromosomal abnormalities)
  • Contrary to some beliefs, trauma does not contribute to the formation of liposarcomas. Current studies also do not support that liposarcomas arise from lipomas (very common, benign fatty tumors)

What are the Signs and Symptoms of Dedifferentiated Liposarcoma?

The signs and symptoms of Dedifferentiated Liposarcomas are mostly dependent upon the location of the tumors. The indications may include:

  • All tumors are slow-growing and painless
  • Dedifferentiated Liposarcoma is frequently found on the abdominal region (retroperitoneum) and the extremities (arms and legs)
  • If the tumor occurs on the thigh, a painless lump may be observed. Thigh tumors may also cause leg pain and restricted movement (walking difficulties)
  • If it forms in the retroperitoneal space, the tumor may not cause any symptoms for a long period of time, until it grows to a large size and compresses the adjacent organs in the abdomen. This is one of the reasons why retroperitoneal tumors remain undetected during their early development stage

How is Dedifferentiated Liposarcoma Diagnosed?

Dedifferentiated Liposarcoma may be diagnosed by using the following tools and procedures:

  • A complete physical examination and thorough evaluation of the individual’s medical history
  • Radiological studies, such as x-ray, whole body CT scan, MRI, or ultrasound scan of the affected region
  • Needle biopsy of tumor
  • Open biopsy of tumor: A tissue biopsy is performed and sent to a laboratory for a pathological examination, who examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis

Note: A needle biopsy may not be helpful, because one may not be able to visualize the different morphological areas of the tumor. Hence, a needle biopsy as a diagnostic tool has certain limitations, and an open surgical biopsy is preferred.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Dedifferentiated Liposarcoma?

Complications from Dedifferentiated Liposarcomas may include the following:

  • Large tumors in the retroperitoneal cavity can lead to weight loss, abdominal pain, frequent urination, and kidney failure due to compression of the kidney
  • Tumors in the leg may result in the formation of varicose veins
  • Metastasis of the tumor to other body regions
  • Damage to the muscles, vital nerves, and blood vessels, during surgery to remove Dedifferentiated Liposarcomas
  • In some cases, recurrence of the tumor after surgery may occur, if the tumor is incompletely removed. Sometimes, the Dedifferentiated Liposarcoma may return as a Well-Differentiated Liposarcoma, for unknown reasons

How is Dedifferentiated Liposarcoma Treated?

Treatment measures for Dedifferentiated Liposarcoma include the following:

  • Complete excision and removal of the tumor with clear margins
  • Radiation therapy and chemotherapy are employed depending upon the specific case
  • Also, in some rare cases, limb amputation may have to be undertaken, in case of limb tumors
  • Post-operative care is important: One must maintain minimum activity levels, until the surgical wound heals
  • Follow-up care with regular screening and check-ups are important, since the tumor can recur in some cases

How can Dedifferentiated Liposarcoma be Prevented?

Current medical research has not established a way of preventing Dedifferentiated Liposarcomas.

What is the Prognosis of Dedifferentiated Liposarcoma? (Outcomes/Resolutions)

  • The prognosis of Dedifferentiated Liposarcoma is good with early detection and surgical removal of the tumor with clear margins
  • Nevertheless, the outcome is dependent upon the site of the tumor. Tumors that can be completely excised have better prognosis than those that cannot be completely removed
  • Statistically, it is seen that about 20% of the tumors metastasize and some tumors are known to recur
  • Typically, the 5 years survival rate is 65%
  • The mortality rate is high, if the tumor is present in the retroperitoneal region, because a complete excision of the tumor is difficult in many cases

Additional and Relevant Useful Information for Dedifferentiated Liposarcoma:

  • In general, liposarcomas form approximately 5% of all sarcomas
  • Despite Dedifferentiated Liposarcoma having a high-grade morphology, the prognosis is better than a high-grade pleomorphic sarcoma

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Oct. 8, 2015
Last updated: Aug. 24, 2018