7 Warning Signs and Symptoms of Synovial Sarcoma You Should Know

Synovial sarcoma is a rare and aggressive type of soft tissue cancer that can develop in various parts of the body, though it most commonly occurs near joints in the arms, legs, and occasionally the trunk. Despite its name, synovial sarcoma does not originate from the synovial tissue that lines joints, but rather from primitive mesenchymal cells. This malignant tumor accounts for approximately 5-10% of all soft tissue sarcomas and typically affects young adults and adolescents between the ages of 15 and 40.

Understanding the symptoms of synovial sarcoma is crucial for early detection and timely medical intervention. While this condition is rare, recognizing its warning signs can significantly impact treatment outcomes. The symptoms can vary depending on the tumor’s location, size, and how rapidly it grows. Many patients initially dismiss early symptoms as minor injuries or common aches, which can delay diagnosis. In this comprehensive guide, we’ll explore the seven most common symptoms of synovial sarcoma to help you identify potential warning signs.

1. A Noticeable Lump or Mass

The most common and often the first symptom of synovial sarcoma is the presence of a palpable lump or mass beneath the skin. This growth typically:

• Appears as a firm, sometimes tender swelling near a joint
• Develops gradually over months or even years
• Ranges in size from a few centimeters to larger masses exceeding 10 centimeters
• May feel deep-seated rather than superficial
• Can be mobile or fixed to surrounding tissue

Many patients describe discovering the lump accidentally while bathing, dressing, or after minor trauma to the area draws attention to it. The mass is usually painless in early stages, which can lead people to mistakenly believe it’s benign. As the tumor grows, it may become more prominent and noticeable. The lump’s consistency is typically firm to hard, distinguishing it from lipomas (fatty lumps) which are usually softer and more movable.

It’s important to note that not all lumps indicate cancer, but any persistent mass that doesn’t resolve within a few weeks or continues to grow should be evaluated by a healthcare professional. The location near joints often causes patients to initially attribute the swelling to sports injuries or arthritis, particularly in younger, active individuals.

2. Pain and Tenderness

While synovial sarcoma may be painless initially, pain develops as the tumor grows and begins to affect surrounding tissues. The pain characteristics include:

• Dull, aching discomfort that gradually worsens over time
• Localized pain at the tumor site
• Sharp or shooting pain when the tumor compresses nearby nerves
• Pain that may intensify with movement or physical activity
• Nighttime pain that can disrupt sleep

The pain mechanism varies depending on tumor location and size. When the tumor presses against nerve structures, patients may experience neuropathic pain characterized by burning, tingling, or electric shock-like sensations. If the tumor involves areas with rich nerve supply, the pain may be more severe and constant.

Some patients report that the pain is initially intermittent and related to specific movements or positions, making it easy to confuse with musculoskeletal injuries or overuse syndromes. As the tumor expands, the pain typically becomes more persistent and may not respond well to over-the-counter pain medications. The tenderness to touch varies among patients—some report significant sensitivity when the area is pressed, while others experience minimal tenderness despite having a sizable tumor.

3. Limited Range of Motion

As synovial sarcoma frequently develops near joints, it can significantly impact joint mobility and function. Patients may experience:

• Decreased flexibility in the affected joint
• Stiffness, especially after periods of rest
• Difficulty performing normal daily activities
• Inability to fully extend or flex the joint
• Sensation of mechanical blocking during movement

The limitation in range of motion occurs through several mechanisms. The tumor’s physical presence can mechanically obstruct joint movement, particularly when it grows within or very close to the joint space. Additionally, the mass effect can cause inflammation in surrounding tissues, leading to stiffness and reduced flexibility.

Athletes and physically active individuals often notice this symptom first, as it directly impacts their performance. For instance, a tumor near the knee might prevent full extension needed for running or jumping, while one near the shoulder could interfere with overhead activities. The progression is typically gradual, and patients may unconsciously adapt their movements to compensate for the restriction, sometimes delaying medical consultation.

This symptom is frequently misdiagnosed as tendinitis, bursitis, or arthritis, particularly in older patients or those with previous joint problems. Physical therapy may be initially recommended, and when symptoms don’t improve, further investigation eventually reveals the underlying tumor.

4. Swelling in the Affected Area

Swelling is a prominent symptom of synovial sarcoma and differs from the tumor mass itself. This symptom manifests as:

• Visible enlargement of the limb or affected body part
• Inflammation of soft tissues surrounding the tumor
• Fluid accumulation (edema) in the area
• Warmth in the swollen region
• Tightness or feeling of pressure in the skin

The swelling results from multiple factors including the tumor’s growth, inflammatory response of surrounding tissues, and potential compression of blood vessels and lymphatic channels. When the tumor interferes with normal fluid drainage, edema can develop in the affected limb, sometimes extending beyond the immediate tumor site.

Patients often notice that clothing, shoes, or jewelry fits more tightly on the affected side. The swelling may fluctuate throughout the day, sometimes worsening with activity or by the end of the day due to gravitational fluid accumulation. In some cases, the swelling can be mistaken for a joint effusion (fluid in the joint) or soft tissue injury.

The degree of swelling varies considerably among patients. Some experience minimal swelling primarily limited to the tumor location, while others develop significant edema affecting a large portion of the limb. When swelling is accompanied by warmth and redness, it can mimic infectious conditions like cellulitis or abscess, potentially leading to initial misdiagnosis.

5. Numbness or Tingling Sensations

Neurological symptoms occur when the synovial sarcoma grows large enough to compress or invade peripheral nerves. These sensations include:

• Tingling (paresthesia) in areas supplied by the affected nerve
• Numbness or reduced sensation beyond the tumor site
• Burning sensations along the nerve distribution
• “Pins and needles” feeling that doesn’t resolve
• Reduced sensitivity to touch, temperature, or pain

These neurological symptoms are particularly significant because they indicate that the tumor is affecting nerve structures, which can have implications for treatment planning and prognosis. The pattern of numbness and tingling typically follows the distribution of specific nerves—for example, a tumor compressing the sciatic nerve might cause symptoms radiating down the back of the leg to the foot.

Unlike temporary paresthesias that resolve quickly (like when your foot “falls asleep”), the neurological symptoms from synovial sarcoma are persistent and progressive. Initially, patients might experience intermittent tingling that comes and goes, but as the tumor grows, the symptoms become constant and may worsen.

Some patients also report hypersensitivity in the affected area, where even light touch feels uncomfortable or painful (allodynia). In advanced cases, muscle weakness can develop in the distribution of the compressed nerve, leading to functional impairment such as foot drop or difficulty gripping objects, depending on which nerve is affected.

6. Visible Changes in Skin Appearance

As the tumor grows, the overlying skin may show various changes that become increasingly noticeable:

• Skin stretching and thinning over the tumor
• Visible veins or vascular patterns on the surface
• Discoloration ranging from redness to purple or bluish hues
• Shiny or glossy appearance of the skin
• Ulceration or skin breakdown in advanced cases

These skin changes reflect the tumor’s effect on superficial tissues and blood flow. As the mass expands, it pushes against the skin from beneath, causing it to stretch. The stretched skin may become translucent, allowing the tumor or enlarged blood vessels to be visible through the surface.

Vascular changes are particularly notable—the tumor may have its own blood supply, and dilated veins may appear on the skin surface as the body attempts to accommodate increased blood flow to the area. Some tumors feel warm to the touch due to increased metabolic activity and blood flow.

In some cases, particularly with large or rapidly growing tumors, the skin’s integrity can be compromised, leading to ulceration. These open sores can be painful, prone to infection, and may drain fluid. Such advanced skin changes usually indicate a larger or more aggressive tumor and warrant urgent medical evaluation.

The skin overlying the tumor may also lose its normal texture and elasticity, feeling tight and taut. Hair growth patterns might change in the affected area, and patients may notice that the skin doesn’t move as freely over the underlying structures as it does on the opposite, unaffected side.

7. Weakness and Functional Impairment

As synovial sarcoma progresses, it can cause significant functional limitations affecting daily activities:

• Muscle weakness in the affected limb
• Difficulty bearing weight or walking (for lower extremity tumors)
• Reduced grip strength or inability to perform fine motor tasks (for upper extremity tumors)
• Fatigue in the affected area with minimal activity
• Compensatory movement patterns leading to secondary problems

Weakness develops through multiple mechanisms. Direct muscle involvement or displacement by the tumor can impair muscle function. Nerve compression or invasion reduces the electrical signals needed for muscle contraction. Additionally, pain and restricted movement lead to disuse atrophy, where muscles weaken from lack of normal activity.

The functional impact varies dramatically depending on tumor location. A synovial sarcoma in the thigh might make walking, climbing stairs, or rising from a seated position difficult. A tumor in the forearm could impair hand function, making it challenging to write, type, or perform work-related tasks. When tumors develop in the foot or ankle, patients may develop altered gait patterns, leading to secondary problems like back pain or pain in the opposite limb from compensation.

Patients often describe a progressive decline in their ability to perform activities they previously did without difficulty. Athletes may notice significant performance decrements, while others might struggle with basic self-care activities like dressing, bathing, or preparing meals. This functional impairment often serves as a major motivator for seeking medical care, as it directly impacts quality of life and independence.

The weakness may be accompanied by muscle atrophy (visible shrinking of the muscles) on the affected side when compared to the unaffected limb, particularly if symptoms have been present for an extended period. This asymmetry becomes increasingly apparent as the condition progresses.

Main Causes of Synovial Sarcoma

The exact cause of synovial sarcoma remains largely unknown, but research has identified several factors associated with its development:

Genetic Chromosomal Translocation: The most significant finding in synovial sarcoma research is the presence of a specific chromosomal abnormality in more than 90% of cases. This involves a translocation between chromosomes X and 18, specifically t(X;18), which creates a fusion gene (SS18-SSX1, SS18-SSX2, or rarely SS18-SSX4). This genetic alteration is considered the hallmark of synovial sarcoma and occurs at the cellular level during development, though it’s not inherited from parents.

Age and Demographics: Synovial sarcoma most commonly affects adolescents and young adults between 15 and 40 years of age, suggesting that developmental factors may play a role. Males are slightly more affected than females, with a ratio of approximately 1.2:1.

Previous Radiation Exposure: In rare cases, synovial sarcoma has been documented to develop in areas previously exposed to radiation therapy for other cancers, typically occurring 10-20 years after radiation treatment. However, this represents a small minority of cases.

Trauma History: Some patients report a history of trauma to the area where the tumor develops. However, it’s unclear whether trauma actually causes synovial sarcoma or simply draws attention to a pre-existing tumor. Most experts believe trauma is coincidental rather than causative.

No Established Environmental Causes: Unlike some other cancers, synovial sarcoma has not been definitively linked to environmental exposures, chemical carcinogens, or lifestyle factors. There is no known association with smoking, diet, or occupational exposures.

It’s important to note that synovial sarcoma is not caused by joint problems, arthritis, or overuse of joints, despite its tendency to occur near joint structures. The term “synovial” is somewhat misleading, as the tumor doesn’t actually arise from synovial tissue.

Frequently Asked Questions

What is the most common first symptom of synovial sarcoma?

The most common first symptom is a painless lump or mass, usually located near a joint in the arms or legs. This mass typically grows slowly over months or years before other symptoms develop.

Is synovial sarcoma always painful?

No, synovial sarcoma is often painless in its early stages. Pain typically develops as the tumor grows larger and begins compressing nerves, blood vessels, or other surrounding structures. About 30-50% of patients report pain at initial diagnosis.

Where does synovial sarcoma most commonly occur?

Synovial sarcoma most frequently develops in the extremities, particularly near the knees, ankles, shoulders, and elbows. Approximately 60-70% occur in the lower extremities, 20-30% in the upper extremities, and the remaining cases can occur in the trunk, head, neck, or rarely in internal organs.

How quickly does synovial sarcoma grow?

Growth rates vary considerably among patients. Some tumors grow very slowly over several years, while others can enlarge rapidly over weeks to months. Biphasic subtypes tend to be more aggressive and grow faster than monophasic subtypes.

Can synovial sarcoma symptoms be mistaken for other conditions?

Yes, symptoms are frequently misdiagnosed initially. The tumor is commonly mistaken for benign conditions such as ganglion cysts, lipomas, hematomas from injuries, bursitis, tendinitis, or arthritis. This often leads to delays in diagnosis averaging 2-4 years from symptom onset.

At what age does synovial sarcoma typically occur?

Synovial sarcoma most commonly affects adolescents and young adults between ages 15 and 40, with the peak incidence in the third decade of life. However, it can occur at any age, including in children and older adults.

Is synovial sarcoma hereditary?

No, synovial sarcoma is not hereditary or passed down through families. The chromosomal translocation that causes it occurs spontaneously in individual cells and is not inherited from parents or passed to children.

When should I see a doctor about a lump?

You should consult a healthcare provider if you notice a lump that: persists for more than 2-3 weeks, continues to grow, is larger than 2 inches (5 cm), is deep-seated or fixed to underlying tissue, is painful, or is accompanied by other symptoms like numbness or weakness. Early evaluation is crucial for optimal outcomes.

Can synovial sarcoma spread to other parts of the body?

Yes, synovial sarcoma can metastasize (spread) to other body parts, most commonly to the lungs (seen in 40-60% of metastatic cases), followed by lymph nodes and bones. This is why early detection and comprehensive treatment are essential.

Are there any warning signs that synovial sarcoma is aggressive?

Warning signs of potentially aggressive behavior include: rapid tumor growth, large size (greater than 5 cm), deep location within tissue, presence of pain, and symptoms suggesting nerve or vascular involvement. However, definitive assessment requires medical imaging and tissue biopsy.

References:

• National Cancer Institute – Synovial Sarcoma
• Mayo Clinic – Soft Tissue Sarcoma
• Cancer Research UK – Synovial Sarcoma
• MD Anderson Cancer Center – Synovial Sarcoma
• National Center for Biotechnology Information – Synovial Sarcoma