Soft tissue sarcoma (STS) is a rare cancer that originates in the supportive, connective tissues of the body, such as muscle, fat, nerves, blood vessels, and fibrous tissue. These tumors can develop anywhere, but their physical presentation depends on their location. While understanding the common physical signs of STS is helpful, only a medical professional can definitively diagnose a mass. This information describes the typical characteristics of a soft tissue sarcoma.
Where Soft Tissue Sarcoma Appears
Soft tissue sarcomas most frequently arise in the arms and legs, accounting for approximately 43% to 60% of all cases. The trunk, including the chest and back region, is another common location. The area behind the abdominal cavity, known as the retroperitoneum, accounts for about 20% of cases. Sarcomas can also occur in the head and neck area, but this is less common.
The tumor’s anatomical location influences how quickly it is discovered. Sarcomas located superficially, near the skin surface in the arms or legs, are often found sooner by the patient or a caregiver. These tumors become noticeable as a visible lump relatively early in their development.
In contrast, sarcomas that develop deep within the retroperitoneum can grow to a substantial size before causing noticeable symptoms. This area contains more space for a tumor to expand without immediately pressing on sensitive structures. Consequently, internal sarcomas often remain undetected until they are quite large.
Physical Characteristics of the Mass
The most frequent sign of a soft tissue sarcoma is the presence of a new or persistent lump or swelling. Sarcomas located in the limbs or torso often present as a mass that is firm and solid to the touch. Unlike many benign lumps, which are easily movable, a sarcoma is more likely to be fixed and difficult to move, especially if it is deep-seated.
Soft tissue sarcomas are commonly diagnosed when they are larger than 5 centimeters, roughly the size of a golf ball. While smaller tumors can be sarcomas, a mass exceeding this 5 cm threshold carries a higher risk of being malignant.
The mass typically demonstrates progressive growth over weeks or months. A lump that is continuously getting bigger, rather than remaining stable or shrinking, raises suspicion.
Initially, a soft tissue sarcoma is often painless, which can delay seeking medical attention. Pain or tenderness may develop as the tumor enlarges and begins to press against nearby nerves, muscles, or blood vessels. This pain is often described as a deep, aching sensation resulting from the physical pressure of the mass.
Non-Mass Symptoms
For sarcomas located internally, particularly in the retroperitoneum, symptoms extend beyond a visible lump. These tumors may not cause pain until they are large enough to interfere with the function of adjacent organs. A sensation of heaviness or fullness in the abdomen can be an early warning sign of a retroperitoneal sarcoma.
As these internal masses grow, they can exert pressure on the digestive tract. This may lead to symptoms such as unexplained abdominal pain, bloating, or changes in bowel or bladder function. A person may also experience early satiety, meaning they feel full quickly after eating.
Systemic effects can also occur. Unintended weight loss and fatigue are sometimes associated with more advanced or high-grade sarcomas. Furthermore, a tumor located in an extremity can compress local blood or lymphatic vessels, leading to swelling in the affected arm or leg.
When to Seek Medical Evaluation
While the majority of soft tissue lumps are benign, certain features suggest the need for prompt medical evaluation. Any new or existing lump that is increasing in size should be examined by a healthcare professional. Rapid growth is a concerning sign that requires immediate investigation.
A mass that is deep-seated, feeling embedded in the muscle or deep tissue, is an important red flag. Any lump measuring greater than 5 centimeters in diameter warrants urgent assessment. The onset of new or persistent pain in a previously painless lump should also trigger a medical consultation.
A professional assessment, which typically includes imaging studies and a tissue biopsy, is the only way to accurately determine if a mass is a soft tissue sarcoma. Seeking an evaluation for a suspicious mass improves the chances of early detection, which significantly influences treatment options and outcomes.