Synovial Sarcoma: Symptoms, Causes, Diagnosis, Treatment, and Prognosis

~Introduction

Synovial sarcoma is a rare and aggressive type of soft tissue sarcoma that primarily affects adolescents and young adults. Despite its name, synovial sarcoma does not originate from synovial tissue (the lining of joints). Instead, it arises from primitive mesenchymal cells that can differentiate into tissues resembling synovium.

Accounting for 5–10% of all soft tissue sarcomas, synovial sarcoma most commonly develops near the joints of the arms or legs, particularly around the knee, ankle, or shoulder. Due to its slow growth and nonspecific symptoms, it is often misdiagnosed in its early stages, delaying treatment.

This article provides a detailed, SEO-optimized overview of synovial sarcoma, including its causes, symptoms, diagnosis, treatment options, prognosis, and current research advancements.

~What Is Synovial Sarcoma?

Synovial sarcoma is a malignant soft tissue tumor that typically develops in the deep soft tissues near joints, tendons, bursae, or muscle sheaths. It is characterized by a specific genetic abnormality involving chromosome translocation t(X;18), which helps distinguish it from other sarcomas.

Key Facts About Synovial Sarcoma

• Rare cancer, often affecting teens and young adults

• Slightly more common in males

• Can occur anywhere in the body

• Known for local recurrence and lung metastasis

~Types of Synovial Sarcoma

Synovial sarcoma is classified into three main histological subtypes:

1. Biphasic Synovial Sarcoma

• Contains both epithelial and spindle cells

• Easier to diagnose under a microscope

• Common presentation

2. Monophasic Synovial Sarcoma

• Composed mainly of spindle cells

• More difficult to distinguish from other sarcomas

• Most common subtype

3. Poorly Differentiated Synovial Sarcoma

• Highly aggressive

• Rapid growth and worse prognosis

• Often seen in advanced disease

~Causes and Risk Factors

Genetic Cause

The defining feature of synovial sarcoma is a chromosomal translocation t(X;18)(p11;q11). This leads to the fusion of the SS18 gene on chromosome 18 with SSX genes on the X chromosome, producing an abnormal protein that drives cancer development.

Risk Factors

• Age between 15 and 40 years

• Male gender (slightly higher risk)

• No strong association with radiation or environmental exposure

• No known inherited predisposition

~ Synovial sarcoma is not contagious and is not caused by lifestyle factors such as smoking or diet.

~Symptoms of Synovial Sarcoma

Symptoms vary depending on tumor size and location. Early-stage disease may remain unnoticed for months or years.

Common Symptoms

• Painless or painful lump near a joint

• Swelling that slowly increases in size

• Reduced range of motion

• Joint stiffness or discomfort

• Numbness or tingling (nerve compression)

Advanced Symptoms

• Persistent pain

• Fatigue and weight loss

• Shortness of breath (if lung metastasis occurs)

• Fractures (rare, when bone is involved)

~Common Locations of Synovial Sarcoma

Although it can arise anywhere, common sites include:

• Lower extremities (especially knee and ankle)

• Upper extremities (shoulder, elbow, wrist)

• Head and neck

• Lung

• Abdominal wall

• Heart (very rare)

~Diagnosis of Synovial Sarcoma

Early and accurate diagnosis is crucial for improving outcomes.

1. Imaging Studies

• MRI: Gold standard for soft tissue evaluation

• CT scan: Useful for detecting lung metastases

• X-ray: May show calcifications

• PET scan: Assesses metabolic activity and spread

2. Biopsy

A core needle biopsy or incisional biopsy is required to confirm the diagnosis. The biopsy must be performed by an experienced sarcoma team to avoid tumor spread.

3. Histopathology and Immunohistochemistry

Tumor cells are tested for markers such as:

• Cytokeratin

• EMA (epithelial membrane antigen)

• BCL-2

• TLE1

4. Molecular Testing

• Detection of SS18-SSX gene fusion using:

  • FISH (Fluorescence In Situ Hybridization)

  • RT-PCR

  • Next-generation sequencing

~Staging of Synovial Sarcoma

Staging depends on:

• Tumor size

• Depth (superficial vs deep)

• Lymph node involvement

• Distant metastasis

The AJCC TNM staging system is commonly used.

~Treatment Options for Synovial Sarcoma

Treatment usually involves a multimodal approach, combining surgery, radiation therapy, and chemotherapy.

1. Surgery

Wide surgical excision with negative margins is the cornerstone of treatment.

• Limb-sparing surgery preferred

• Amputation is rare and reserved for advanced cases

• Reconstruction may be required

2. Radiation Therapy

Radiation therapy reduces local recurrence risk.

• Preoperative radiation: Shrinks tumor, smaller field

• Postoperative radiation: Targets residual cancer cells

3. Chemotherapy

Synovial sarcoma is more chemo-sensitive than many other sarcomas.

Common regimens include:

• Ifosfamide

• Doxorubicin

• Combination chemotherapy for high-risk or metastatic disease

4. Targeted Therapy and Immunotherapy

Emerging treatments include:

• Pazopanib (approved for advanced soft tissue sarcoma)

• T-cell receptor (TCR) therapies targeting NY-ESO-1

• Clinical trials exploring novel agents

~Prognosis and Survival Rate

Prognosis depends on several factors:

Positive Prognostic Factors

• Tumor size <5 cm

• Complete surgical resection

• Younger age

• No metastasis at diagnosis

Negative Prognostic Factors

• Large tumor size

• Lung metastasis

• Poorly differentiated subtype

• Incomplete excision

Survival Rates

• 5-year survival rate: ~60–70%

• 10-year survival rate: ~50–60%

• Local recurrence occurs in up to 30% of cases

• Lung metastasis is the most common distant spread

~Recurrence and Metastasis

Synovial sarcoma has a high risk of late recurrence, sometimes even 10–20 years after initial treatment.

Common Metastatic Sites

• Lungs (most common)

• Lymph nodes

• Bone

• Liver (rare)

Long-term follow-up is essential.

~Living With Synovial Sarcoma

Follow-Up Care

• Regular imaging (MRI, CT chest)

• Physical examinations

• Monitoring for late effects of therapy

Quality of Life

• Physical therapy after surgery

• Pain management

• Psychological counseling

• Support groups for sarcoma patients

~Synovial Sarcoma in Children and Adolescents

• Represents one of the most common non-rhabdomyosarcoma soft tissue sarcomas in youth

• Often diagnosed late due to misinterpretation as sports injuries

• Treatment principles similar to adults

• Long-term survivorship care is crucial

~Current Research and Clinical Trials

Ongoing research is focused on:

• Personalized medicine

• Gene-targeted therapies

• Immunotherapy approaches

• Early detection biomarkers

Patients are encouraged to discuss clinical trial participation with their oncologist.

~Prevention and Screening

Currently, there is no known way to prevent synovial sarcoma and no routine screening tests. Early evaluation of persistent or enlarging soft tissue masses is key.

- Any lump larger than 5 cm, deep-seated, or growing should be evaluated by a specialist.

~Frequently Asked Questions (FAQs)

Is synovial sarcoma curable?

Yes, especially when detected early and completely removed surgically.

Is synovial sarcoma hereditary?

No, it is not inherited and does not run in families.

How fast does synovial sarcoma grow?

It typically grows slowly but can become aggressive over time.

Can synovial sarcoma spread to the lungs?

Yes, the lungs are the most common site of metastasis.

~Conclusion

Synovial sarcoma is a rare but serious soft tissue cancer that predominantly affects young individuals. Advances in imaging, molecular diagnostics, and multimodal treatment have significantly improved outcomes. However, due to its tendency for recurrence and metastasis, early diagnosis, expert management, and long-term follow-up are essential.

With ongoing research and emerging therapies, the future holds promise for more targeted and effective treatment options for synovial sarcoma patients.