Although there are many different forms and subtypes of sarcoma, some that can affect both soft tissue and bone, sarcomas of the bone are an exceptionally rare form of cancer, accounting for approximately 3,000 out of a total 1,685,210 estimated cancer diagnoses each year (including all forms) according to the the American Cancer Society. Undifferentiated pleomorphic sarcoma (UPS) can develop either in soft tissue (muscle, tendons, cartilage, ligaments, the lining of blood vessels, and fat) or in bone tissue in adults and requires expert pleomorphic sarcoma treatment.
While they can technically develop anywhere in the body, sarcomas are most common in the long bones of the arms and legs, and the abdomen and pelvis, depending on the type. A skilled Los Angeles orthopedic oncology surgeon can evaluate the location and type of tumor in order to determine the best pleomorphic sarcoma treatment.
What is Undifferentiated Pleomorphic Sarcoma?
Also known as malignant fibrous histiocytoma (MFH), this type of sarcoma occurs almost exclusively in adults (although rare cases have been diagnosed in children as well, commonly at the top of the tibia near the knee). Healthy cells go through a normal cycle where they eventually die off and make room for new cells. Tumors result from a malfunction in this process, where a mutation, damage to a gene, and other triggers interrupt this cycle and cause the cells to keep proliferating instead of dying off.
When tumors develop, they are categorized by studying the cells of the tumor under a microscope to observe their behavior (how likely they are to grow and spread to other parts of the body, whether they are fast or slow moving, and whether they have already spread to other locations like the lymph nodes). Tumors are then assigned a stage and grade, which helps to determine the best course of pleomorphic sarcoma treatment and a general prognosis in Los Angeles.
Studying tumors under a microscope, specifically the type and percentage of healthy tissue that the tumors resemble, is how sarcomas and all forms of cancer are classified, meaning whether it is a type of lymphoma, melanoma, leiomyosarcoma, or myeloma. With undifferentiated tumors, the malignant cells do not form clear patterns of resemblance to healthy tissue, therefore making them much harder to identify and classify.
The pathology and oncology team can tell that the cells are malignant, but assigning a definitive classification can be difficult. For this reason, malignant fibrous histiocytoma/undifferentiated pleomorphic sarcoma is also referred to as a diagnosis of exclusion, meaning the diagnosis is assigned through something like the process of elimination, when other forms of cancer have been ruled out (especially on the rare occasions that it is diagnosed in pediatric patients).
Undifferentiated pleomorphic sarcoma is suspected to have developed from primitive mesenchymal (stem) cells that can differentiate into fibroblasts, histiocytes, osteoclasts, and myofibroblasts. It is slightly more common in men and usually occurs in patients over the age of 60. For more information about pleomorphic sarcoma of the bone treatment, visit nih.gov.
Bone and soft tissue sarcomas can be difficult to diagnose in the early stages due to their location deep in connective tissue, which has more flexibility to stretch and expand with the growth of a tumor. The most common symptoms of pleomorphic sarcoma are usually a painless mass or lump, although they have the potential to cause pain if they are close enough to put pressure on a nerve. Other general symptoms of bone sarcomas include:
- Bone fractures
- Unexplained weight loss
- Swelling and tenderness at tumor site
Diagnostic imaging tests are usually ordered to determine whether a mass is malignant or benign (generally speaking, the majority of lumps and masses are usually not cancerous, but it is important to obtain an exam and proper diagnosis for any lumps or growths that persist for a prolonged period of time to rule it out). The most common diagnostic tests are:
- CT scan
- PET scan
- Bone scan
Treating UPS/MFH of the Bone
Undifferentiated pleomorphic sarcoma is usually aggressive with a generally high risk of localized recurrence. Although metastasis of this type of cancer can be rare, the most common distant site of metastasis is the lungs. There are several treatment options for UPS depending on the circumstances:
- Limb Preservation/localized tumor excision surgery – Most incidences of undifferentiated pleomorphic sarcoma of bone develop in the femur and tibia, followed by the arms. When possible, the affected portion of the bone is removed in surgery, leaving the remaining healthy bone and limb intact. If a large portion of the bone is affected, amputation may be necessary (rare).
In some cases, UPS is diagnosed outside of the limbs, like in the ribs or pelvis, and surgery may also be used to remove localized tumors.
Sarcoma Treatment and Orthopedic Oncology Surgery in Los Angeles
Daniel C. Allison, MD, FACS, MBA, is the Assistant Director of Orthopedic Oncology at Cedars-Sinai Sam Oschin Cancer Center in Los Angeles. Dr. Allison specializes in diagnosis and sarcoma treatment, including limb preservation, for rare bone sarcomas in both children and adults. For more information, contact the office of Dr. Allison by calling 310-730-8008 to schedule an appointment today.
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