Malignant Fibrous Histiosarcoma (undifferentiated pleiomorphic sarcoma)

Malignant Fibrous Histiocytoma is a sarcoma (malignant tumor) that can start in the bone or the soft tissue. MFH is the most common type of soft tissue sarcoma of the extremity while MFH of bone is fairly rare. It occurs more frequently in someone who is in their 50s and is a bit more common in men than women1.

The origin of the tumor is not known, meaning that the type of cell that this tumor arises from hasn’t been determined. Until 2002 this type of extremity sarcoma was called Malignant Fibrous Histiosarcoma (MFH) but in 2002, the World Health Organization changed the description of this type of tumor, renaming it undifferentiated pleomorphic sarcoma because of the inability to identify a specific cell type2 It is still often referred to as MFH.

There have been a number of ‘sub-types’ of MFH described over the past 20 years based on the variety of cell types seen in the tumor tissue. These include:

Signs and Symptoms of Osteosarcoma

  • Storiform-Pleomorphic MFH– the majority of MFH diagnosed cases are of this type.
  • Myxoid MFH - 2nd most common type of MFH.
  • Giant Cell MFH – 3rd most common type.
  • Angiomatoid MFH – more often diagnosed in children and adolescents.
  • Inflammatory MFH – rarest type of MFH.

Signs and Symptoms of undifferentiated pleiomorphic sarcoma/MFH

  • Pain– pain in the area of the tumor.
  • Swelling - a soft tissue mass may be present and it could be red and warm to the touch; often, the mass has been growing rapidly.

Cause of undifferentiated pleiomorphic sarcoma/MFH

There is no known cause of MFH but other conditions may be related. These include:

  • Radiation for another malignancy
  • History of Paget’s disease
  • History of non-ossifying fibroma
  • History of fibrous dysplasia
  • Werner syndrome (soft tissue sarcoma)
  • Gardner syndrome(soft tissue sarcoma)
  • Li Fraumeni syndrome(soft tissue sarcoma)
  • Von Recklinghausen disease (soft tissue sarcoma)

Diagnosing undifferentiated pleiomorphic sarcoma/MFH

Because MFH is most often a soft tissue sarcoma, an x-ray may not show the tumor. MRI is typically necessary to determine if there is a tumor in the area and the full extent of the tumor.

Once a soft tissue sarcoma is suspected, it is important that a physician with expertise in diagnosis and management of extremity tumors be consulted before any other diagnostic testing is done.

      MRI     An MRI enables the doctors to better see the full extent of the tumor. It is important to know if the tumor is ‘invading’ other tissues as treatment plans (such as surgical options) are being considered.
      CT scan A CT (CAT) scan can help to show the amount of bone destruction that the lesion is causing.
  Biopsy A biopsy is necessary to determine the exact type of tumor as well as its grade (aggressiveness). It is important that the biopsy be done by a specialist experienced in appropriate biopsy of extremity tumors. A biopsy done incorrectly may limit surgical options, and in some cases make amputation the only surgical option.
  PET/CT scan This test is another that is necessary for staging of the cancer. It reveals if the cancer has metastasized to the abdomen, brain or other areas of the body

Grading and Staging of undifferentiated pleiomorphic sarcoma/MFH

It is important to know how aggressive a sarcoma is (the grade of the sarcoma) as well as the stage of the cancer (has it spread to other areas of the body). This information helps the physicians in determining the best approach to treatment, as well as assisting in discussions about prognosis.

MFH Grade – the grade of the MFH tumor is the most important indicator in prognosis for soft tissue sarcoma3.

    Low grade (G1) low likelihood of growing and spreading to other areas of the body.
    Intermediate grade (G2) moderate likelihood of growing and spreading.
  High grade (G3) most aggressive type so likely to grow and metastasize.

MFH Stage – staging combines the information from the diagnostic testing to determine the extent or severity of the disease process. The size of the tumor, if it has spread to other area such as the lungs, and the grade are all considered when determining the stage. MFH staging is from I (one) to IV (four) with stage I meaning the tumor is localized (only in the original site) and stage IV indicating that the tumor has metastasized to other areas of the body.

    Stage I     The tumor is low to intermediate grade and has remained local, meaning that it is only at the site where it was originally located.
     Stage II & III The tumor is higher grade, but has not spread to the lymph nodes.
  Stage IV The tumor has metastasized to lymph nodes and other sites in the body.

Treatment of undifferentiated pleiomorphic sarcoma/MFH

Surgery – the goal of treatment is to remove the tumor so it is unable continue growing or to spread to other areas of the body through the blood stream or lymph system. The goal is to remove the entire tumor, along with a layer (margin) of normal tissue surrounding the tumor. The reason for removing this normal layer of tissue is to assure that all the cancerous tissue has been removed. In the event that a normal layer cannot be removed amputation may be considered. When the tumor is in an area that adequate removal or amputation isn’t possible, surgery with chemotherapy may be considered. The chemotherapy in this circumstance is to minimize the potential for recurrence or spread that could be possible because the entire tumor could not be removed.

Radiation therapy – this is the use of radiation to kill cancer cells or keep them from growing. It’s not effective in all types of cancer but with soft tissue sarcoma it has been shown to decrease the chance that the tumor will come back in the original site4. Whether a course of radiation therapy is recommended before or after surgery is dependent on individual situations and tumor type.

Chemotherapy – “chemo” has limited effectiveness in treatment of soft tissue sarcoma. As mentioned above, it may be considered when adequate surgical removal isn’t possible. There are more investigational medications and clinical trials becoming available for treatment of soft tissue sarcoma.

For MFH of bone rather than soft tissue, the treatment approach is similar to that of Osteosarcoma with chemotherapy followed by surgical removal, then chemotherapy after removal.

Resection Removal of the tumor without “rebuilding” the area that the tumor was removed from, more common in pelvic tumors than tumors in the extremity
Resection with reconstruction Removal of the tumor and “rebuilding” with metal implants and/or bone allografts; soft tissue reconstruction may also be necessary
+Amputation Removing the extremity at a level above the tumor

Prognosis of undifferentiated pleiomorphic sarcoma/MFH

Prognosis, or chance of recovery, is determined by grade of the tumor at the time of diagnosis, as well as the patient’s age, the size of the tumor, and the stage (if there was metastatic disease at the time of diagnosis). In general, poorer prognosis is associated with high grade tumors or in a person with stage III or IV disease. Other factors associated with poorer prognosis are if the patient is older than 60 years old or if the tumor is over 5cm. Low grade tumors are usually curable by surgery.


1. Nasciemento AF, Raut CP; Diagnosis and management of pleomorphic sarcomas (so-called “MFH”) in adults. J Surg Oncol, 2008 Mar15;97(4):330-9

2. World Health Organization Classification of Tumors: Pathology and Genetics of Tumors of Soft Tissue and Bone. Edited by Fletcher CDM, U. K., Mertens F., Lyon, France, IARC Press, 2002

3. Coindre JM; Grading of soft tissue sarcomas: review and update. Arch Pathol Lab Med. 2006 Oct;130(10):1448-53

4. Barkley, H. T., Jr.; Martin, R. G.; Romsdahl, M. M.; Lindberg, R.; and Zagars, G. K.: Treatment of soft tissue sarcomas by preoperative irradiation and conservative surgical resection. Int J Radiat Oncol Biol Phys, 14(4): 693-9, 1988

5. Pezzi CM, Rawlings MS Jr, Esgro JJ, Pollock RE, Romsdahl MM.; Prognostic factors in 227 patients with malignant fibrous histiocytoma. Cancer. 1992 Apr 15;69(8):2098-103