Low-Grade Fibromyxoid Sarcoma – Low Grade Fibromyxoid Sarcoma

Other known names:

• Hyalinizing Spindle Cell Tumor with Giant Rosettes
• LGFMS (Low-Grade Fibromyxoid Sarcoma)
• LGFS (Low-Grade Fibromyxoid Sarcoma)

What Is Low-Grade Fibromyxoid Sarcoma?

• Low-grade fibromyxoid sarcoma, abbreviated LGFS in this article, is a rare malignant soft tissue tumor that generally occurs in young adults. Tumors are most often located in the extremities (arms and legs) or the chest and back.
• Although no risk factor has been identified for this soft tissue tumor, its cause is associated with genetic defects. In particular, fusion of the FUS and CREB3L2 (or CREB3L1) genes is a characteristic feature of LGFS.
• Low-grade fibromyxoid sarcoma usually grows slowly and is painless in most cases. If the disease recurs after treatment and metastasizes , this may often occur several years after initial treatment and tends to involve the lungs.
• The main treatment for LGFS is complete surgical excision, meaning wide surgical removal of the tumor. However, careful long-term follow-up is necessary for recurrence and/or metastasis.
• The prognosis of this soft tissue tumor depends on various factors, including its location, size and stage. Small tumors detected early and completely removed generally have a good prognosis.

Who Tends to Develop Low-Grade Fibromyxoid Sarcoma? (Age and Sex Distribution)

• Low-grade fibromyxoid sarcoma is a rare malignancy, with only 350 cases reported so far. Some sources report 0.18 cases per million people and that it accounts for %0.6 of all soft tissue tumors. However, many cases may remain unreported.
• It can occur at any age, but LGFS is most common in young adults. Of every 5 cases, 1 occurs in individuals younger than 18.
• It affects both men and women, and no sex preference has been reported.
• No particular racial or ethnic group preference is seen.
• Some data also suggest its frequency has increased in recent years, but its rarity makes this difficult to establish, and improvements in diagnostic methods may also contribute.

What Are the Risk Factors for Low-Grade Fibromyxoid Sarcoma?

No risk factors for low-grade fibromyxoid sarcoma have currently been identified.

What Causes Low-Grade Fibromyxoid Sarcoma? (Etiology)

The exact cause and mechanism of low-grade fibromyxoid sarcoma are unknown. However, the following genetic abnormalities have been observed:

• Chromosomal translocations occur in% 65 of cases; another % 25 are known to show ring chromosome abnormalities. Research is investigating how these two factors lead to gene fusion.
• In %76-96 of patients, fusion of FUS and CREB3L2 is detected in the tumor; in % 4-6, fusion of FUS and CREB3L1 is detected.

What Are the Symptoms of Low-Grade Fibromyxoid Sarcoma?

Signs and symptoms may vary depending on tumor location. Symptoms of low-grade fibromyxoid sarcoma may include:

• A painless, slow-growing mass may be noticed in the body. Research shows that of every 6 people diagnosed with LGFS, 1 has carried the tumor for a long time, even 5 years.
• Tumor size ranges from 1-20 cm; the average size at diagnosis is approximately 5 cm.
• Tumors may lie immediately beneath the skin, particularly in children, but most often arise deeper than the subcutaneous tissues. - The most common LGFS locations are the arms and legs (proximal regions), or the chest and back. They may also occur elsewhere.

How Is Low-Grade Fibromyxoid Sarcoma Diagnosed?

LGFS is diagnosed using the following tools:

• Physical examination with assessment of the individual’s medical history
• Computed tomography or magnetic resonance scanning of the affected area
• Tissue biopsy of the tumor: a sample is taken from the tumor and sent to a laboratory for pathological examination. The pathologist examines the biopsy under a microscope. After considering the clinical findings, special tissue studies if needed, and microscopic findings together, the pathologist makes a definitive diagnosis.

Note:

• LGFS is among the very rare cancers, so its pathological diagnosis is often difficult.
• It was previously called a hyalinizing spindle cell tumor with giant rosettes because the tumor forms an unusual pattern on microscopic examination.

What Are the Possible Complications of Low-Grade Fibromyxoid Sarcoma?

• The tumor has a low risk of metastasis and recurrence in the first 5 years after surgical removal of the primary tumor. Metastasis and recurrence rates are % 5 and% 10, respectively. 
• However, some studies report that both metastasis and recurrence are more frequent today than previously. 
• LGFS tends to metastasize to the lungs and their lining (pleura).

How Is Low-Grade Fibromyxoid Sarcoma Treated?

• Because it is a malignant tumor with metastatic potential, wide surgical removal of the entire tumor is the main treatment.
• Embolization, blocking the vessels supplying the tumor with a clot, may be used to temporarily relieve signs and symptoms and reduce blood loss during surgery.
• Radiation therapy and/or chemotherapy may be used to reduce symptoms caused by metastatic disease and extend survival. Conventional chemotherapy regimens used for sarcoma are less effective in LGFS; trabectedin (Yondelis) is one of the most effective chemotherapy agents for this disease.
• Long-term follow-up care with regular screening and checkups is important.

What Is the Prognosis of Low-Grade Fibromyxoid Sarcoma? (Disease Course and Outcomes)

• Low-grade fibromyxoid sarcoma is a very rare low-grade cancer with metastatic potential. Here, “low grade” indicates that cancer cells do not have an aggressive proliferation potential. Prognosis depends on many factors, including tumor size, stage and location, as well as the person’s age and health.
• Small LGFS tumors completely removed surgically generally have a good prognosis. Metastasis is uncommon, but prolonged follow-up is required.
• However, tumor behavior is difficult to predict because LGFS can follow an aggressive course despite being low grade. 
• After removal of the primary tumor, recurrence and/or metastasis are known to occur in some cases after approximately 5 years; a case developing metastasis after 45 years has even been reported in the literature.

In conclusion, low-grade fibromyxoid sarcoma is a very rare soft tissue cancer. The main treatment for LGFS, which is more common in young adults, is wide surgical removal of the tumor. Because this disease is known to be closely associated with genetic defects involving gene fusion, medical follow-up should not be discontinued given the possibility of long-term recurrence.