Undifferentiated pleomorphic sarcoma (UPS)

Undifferentiated pleomorphic sarcoma is often found as a painful, fast growing lump anywhere in the body, although they are more common in the legs. Under the microscope the cells appear undifferentiated, which means they don’t look like any normal mature cell. Pleomorphic means there will be a mixture of different forms of cell. These tumours are also genetically variable, so it is very hard to say what type of cell the cancer started in other than it came from the soft tissue.

A diagnosis of UPS is sometimes called a “diagnosis of exclusion” where it is used to label any soft tissue tumour that doesn’t fit any other description.