Well-Differentiated Liposarcoma

Well-differentiated liposarcoma (WDLS) typically affects adults, most commonly between the ages of 50 and 60, and is more frequently seen in males.

This type of liposarcoma presents as a slow-growing, painless mass, which is usually located in the retroperitoneum (the area behind the abdominal cavity) or in the limbs. Less commonly, it may appear in the spermatic cord or mediastinum (the area between the lungs). The mass itself can vary in consistency, ranging from soft and fleshy to firm.

WDLS closely looks similar to normal fat tissue but often has thicker fibrous bands and some irregular or enlarged cells. While WDLS itself does not metastasize (spread to other regions in the body), it carries a risk of growing or spreading into a more aggressive and malignant form called dedifferentiated liposarcoma.

Dedifferentiated liposarcoma is associated with increased local recurrence and a higher likelihood of metastasis.

The prognosis for WDLS largely depends on the tumor's location. For WDLS in the extremities, the outlook is generally favorable after surgical removal, with low rates of recurrence and almost no associated mortality. The 5-year survival rate is 83% for well-differentiated retroperitoneal liposarcoma.

Symptoms of well-differentiated liposarcoma can vary depending on the size and location of the tumor. Common symptoms may include:

• Painless lump or mass in the arms, legs, or abdomen
• Discomfort if the tumor starts pressing on nearby nerves, muscles, or organs
• Swelling in the affected area 
• Abdominal pain, bloating, or a sense of fullness
• Fatigue
• Unexplained weight loss

Well-differentiated liposarcoma is characterized by significant changes in chromosomes. The most notable change is the amplification of the chromosomal region 12q13-15, which occurs in approximately 90% of cases. This means the number of copies of genes in the 12q13-15 region of a genome increases, leading to uncontrolled cell growth and tumor development.

This amplification leads to the overexpression of three genes that promote cell growth: 

• MDM2 blocks a natural defense that stops tumors.
• CDK4 controls how cells grow and divide.
• HMGA2 helps regulate cell growth but can contribute to tumor formation when overactive.

Inherited genetic conditions, such as hereditary retinoblastoma or Li–Fraumeni syndrome, can increase the risk of WDLS. Other factors that may increase the risk of developing this type of liposarcoma include: 

• Exposure to certain chemicals
• Past history of radiation therapy for cancer
• Damaged lymphatic system

Well-differentiated liposarcoma is diagnosed using a comprehensive approach involving several diagnostic tests to evaluate the tumor's characteristics and location.

• Physical Examination: During the initial consultation, your doctor checks for any visible or palpable lumps or masses. 
• Imaging: Imaging tests, such as a CT scan or MRI, are performed to evaluate the size, extent, and location of the tumor. These tests can also help determine whether the tumor has spread to surrounding tissues or other parts of the body.
• Biopsy: A biopsy is crucial for confirming the diagnosis of WDLPS. A tissue sample is obtained from the mass, often using an image-guided needle biopsy, to examine the cells under a microscope.
• Molecular and Genetic Testing: These specialized tests analyze the tumor's genetic and molecular profile to better understand its type and behavior. For WDLPS, molecular testing can identify specific chromosomal aberrations, such as the amplification of the 12q13-15 region.

Surgery is the primary treatment for well-differentiated liposarcoma and is often the most effective approach. During surgery, the goal is to remove the tumor along with a margin of healthy tissue surrounding it. This practice helps ensure that any microscopic cancer cells not visible to the naked eye are also removed, reducing the risk of recurrence.

Complete tumor excision is often possible for tumors located in the extremities. However, tumors in more complex areas, such as the retroperitoneum or groin, are more challenging to treat. These locations carry a higher risk of local recurrence and the possibility of transformation into dedifferentiated liposarcoma.

Radiation therapy may be used alongside surgery, particularly in such cases where achieving clear margins is difficult or if the tumor is located in a sensitive area.

Chemotherapy is generally not effective for WDLS.

Ongoing clinical trials are exploring innovative therapies, including CDK4 and MDM2 inhibitors, for patients with advanced cases. These emerging treatments offer hope for improving outcomes in challenging cases.

At the Sarcoma Oncology Center, we create personalized treatment plans tailored to each case. Key factors such as the tumor's size, location, progression, and biopsy results guide our approach. For cases of WDLS where traditional treatments are not effective, we offer access to innovative clinical trials, providing advanced options to improve outcomes.

At our office in Santa Monica, we design personalized and innovative plans for treating well-differentiated liposarcoma.

To schedule a consultation, please call us at 424-699-3862 or request an appointment online.