What is Undifferentiated Pleomorphic Sarcoma?

In this blog, we’ll be providing an overview of a soft tissue sarcoma we treat at Baylor Scott & White Greater Dallas Orthopaedics called undifferentiated pleomorphic sarcoma or UPS. Like all soft tissue sarcomas, UPS is exceedingly rare, and like most sarcomas, is more common among those of advanced age. Among soft tissue sarcomas, it’s the fourth-most common, with just a few thousand cases diagnosed each year.

The name of UPS has changed over time and its current designation, undifferentiated pleomorphic sarcoma, is very descriptive. Undifferentiated indicates that the cancer cells do not resemble the cells of the surrounding healthy tissue at all when viewed under a microscope. Pleomorphic indicates that these cancer cells grow in all shapes and sizes, rather than conforming to a consistent presentation.

Undifferentiated Pleomorphic Sarcoma

Undifferentiated pleomorphic sarcoma, formerly known as malignant fibrous histiocytoma, is a soft tissue cancer most often found in the arms and legs but is found in the abdomen and pelvis in a minority of cases. Unlike some sarcomas we’ve discussed recently, UPS is typically fast-growing and is known to quickly spread to areas of the body like the lungs and organs nearest to the first affected region. 

 

What are the Causes of Undifferentiated Pleomorphic Sarcoma?

Unfortunately, it is not fully known what causes UPS to occur, but continuing research is being done regarding this topic. While it makes up a minority of cases, UPS is one of the most common sarcomas to occur at the site of previous radiation treatment.

 

Who is Most Affected by Undifferentiated Pleomorphic Sarcoma?

As many sarcomas treated at Baylor Scott & White Greater Dallas Orthopaedics, UPS disproportionately impacts individuals over the age of about 50 and occurs twice as often with males compared to females. However, anyone at any age can suffer from undifferentiated pleomorphic sarcoma.

As mentioned in the previous point, another critical factor to consider is whether an individual has been treated with radiation therapy, as this makes them slightly more likely to develop UPS in the treated location.

What are the Symptoms of Undifferentiated Pleomorphic Sarcoma?

Because UPS can develop virtually anywhere in the body, the symptoms are somewhat specific to the locality. Generally, there is the swelling and growth of a lump, which can either become more painful or more numb as it gets larger. Fever and weight loss are common regardless of the location of the tumor.

As we discussed, UPS is common in the arms & legs, and in those cases, patients often notice swelling in the hands or feet of the impacted limb, even if the tumor itself is located elsewhere in the extremity. 

When the pelvis or abdomen is impacted, loss of appetite and/or constipation is not uncommon.

 

How is Undifferentiated Pleomorphic Sarcoma Treated?

Just like the symptoms of UPS, the treatment strategy for undifferentiated pleomorphic sarcoma is also largely dependent on the location of the tumor. In some areas of the body, surgical intervention is the most direct and most effective course of treatment. In other areas of the body, a treatment plan predicated on radiation and pharmaceuticals is prescribed.


We hope this overview of undifferentiated pleomorphic sarcoma was insightful and enlightening. The team at Baylor Scott & White Greater Dallas Orthopaedics places a high value on informing our audience and improving the medical literacy of all we impact.

As always, the content of a blog post is no substitute for a legitimate medical diagnosis. If you are concerned that you or a loved one may be suffering from a bone or soft tissue tumor, prioritize an appointment with a qualified medical professional at your earliest availability.