Undifferentiated Pleomorphic Sarcoma – Symptoms and Causes
Overview
Undifferentiated pleomorphic sarcoma (UPS) is a rare cancer that primarily affects soft tissues in the body. These soft tissues play important roles in connecting and supporting various body structures.
UPS most commonly develops in the arms or legs, though it can occasionally appear in the retroperitoneum (the space behind the abdominal organs).
The name of this cancer describes its appearance under microscopic examination:
- Undifferentiated: The cancer cells don’t resemble the normal tissues where they develop.
- Pleomorphic: The cells show various shapes and sizes.
This condition was previously known as malignant fibrous histiocytoma.
Symptoms and Warning Signs
Undifferentiated pleomorphic sarcoma shows different symptoms based on where it forms in the body. This cancer most commonly affects the arms and legs, but can develop anywhere.
Common symptoms include:
- A growing lump or swollen area, often deep under the skin
- Firm or fixed mass that may feel painless at first
- Skin changes over the lump (shiny, stretched, or discolored)
- Pain, tingling, or numbness, especially as the tumor presses on nerves
- Swelling in the limb or extremity (e.g., hand, foot) when the tumor blocks circulation
- Restricted movement or joint stiffness if the tumor is near a joint
- Abdominal pain, bloating, reduced appetite, and constipation if located in the abdomen
- Unexplained fever or persistent low-grade fevers
- Unintentional weight loss
- Fatigue or general malaise
Many people do not experience symptoms until the tumor has grown significantly, which can delay diagnosis.
When to Contact a Healthcare Provider
If you notice any lasting symptoms that concern you, schedule an appointment with your doctor right away. Persistent lumps or unexplained swelling should never be ignored, especially if they’re growing or causing discomfort.
Causes
The exact cause of undifferentiated pleomorphic sarcoma remains unknown. Research shows this cancer begins with DNA mutations in a single cell. These genetic changes disrupt normal cellular functions.
When DNA mutations occur, they instruct cells to multiply uncontrollably. This rapid growth creates a tumor made of abnormal cells.
These aggressive cells can:
- Invade nearby healthy tissues
- Destroy surrounding structures
- Break away from the original tumor
- Travel through the bloodstream
- Form new tumors in distant body parts (metastasis)
Common sites for metastasis include the lungs and bones. Scientists continue studying these genetic changes to better understand how this rare cancer develops.
Risk Factors
Several factors may raise the chance of developing undifferentiated pleomorphic sarcoma:
- Age over 50: This cancer appears more frequently in older adults, though it can affect people of any age.
- History of Radiation Treatment: In rare cases, this cancer develops in body areas previously treated with radiation therapy.
Most people who get this cancer have no known risk factors. Many individuals with these risk factors never develop the disease.
