Overview

Undifferentiated pleomorphic sarcoma (UPS) is a rare type of cancer that begins mostly in the soft tissues of the body. Soft tissues connect, support and surround other body structures.

UPS usually occurs in the arms or legs. Less often it can happen in the area behind the abdominal organs (retroperitoneum).

The name undifferentiated pleomorphic sarcoma comes from the way the cancer cells appear under the microscope. Undifferentiated means the cells don't look like the body tissues in which they develop. The cancer is called pleomorphic (plee-o-MOR-fik) because the cells grow in multiple shapes and sizes.

Treatment for UPS depends on the location of the cancer, but often involves surgery, radiation and drug treatments.

UPS used to be called malignant fibrous histiocytoma.