types of soft tissue sarcoma
Alveolar soft part sarcoma (ASPS) is a rare, poor prognosis neoplasm of unknown histogenesis with a distinctive histology, specific molecular characteristics, and unique clinical behaviors. ASPS generally develop in younger patients. Unlike other soft tissue sarcomas, ASPS also metastasizes to the brain. While surgery can improve outcomes even in the setting of metastatic disease, traditional chemotherapeutic agents and ⁄or radiotherapy have failed to demonstrate significant survival advantages. This article provides an overview of the clinical manifestations, diagnosis, radiographic features, and treatment of ASPS.
Angiosarcoma is a cancer of the inner lining of blood vessels, and it can occur in any area of the body. The disease most commonly occurs in the skin, breast, liver, spleen, and deep tissue. Angiosarcoma of the skin, or cutaneous angiosarcoma, makes up the majority of angiosarcoma cases, and it is usually found on the scalp and face. Angiosarcoma that appears underneath the surface of the skin is called subcutaneous angiosarcoma. Approximately 25% of angiosarcomas are found in deep tissue, and around 8% are found in breast tissue.
Angiosarcomas occur in men and women of all races, and they are rare in children. Patients with angiosarcoma are best treated at a cancer center where an expert sarcoma team and resources are available to provide specialized and responsive care.
Clear cell sarcoma of soft tissue, not to be confused with clear cell sarcoma of the kidney, is a rare type of cancer primarily affecting young adults between 20 to 40 years old. Sarcomas are cancers that arise within connective tissues, such as bone, muscle, fat, and tendons. Clear cell sarcoma tumors tend to grow attached to tendons in the limbs, especially in the feet and hands. They sometimes develop in the gastrointestinal tract, attached with the bottom layers of the skin, and in locations throughout the torso. Clear cell sarcoma is slightly more common in females than in males.
Clear cell sarcoma is a translocation-associated sarcoma, which means that a genetic mutation defines the disease. In chromosomal translocations, the pieces of two chromosomes are swapped, which can result in an abnormal fusion of genes.
There are two ways to classify clear cell sarcoma tumors: by site or by translocation type. Types of clear cell sarcoma based on site of origin are:
typical clear cell sarcoma of tendons and aponeuroses (layers of flat broad tendons)
gastrointestinal clear cell sarcoma
cutaneous clear cell sarcoma (of the skin)
By genetic classification, the most common types are clear cell sarcoma harboring an EWSR1/ATF1 or a EWSR1/CREB1 translocation. Sometimes, tumors have no observed EWSR1 translocation.
Chondrosarcoma is a type of sarcoma that affects the bones and joints. It is a rare cancer that accounts for about 20% of bone tumors and is diagnosed in approximately 600 patients each year in the United States. Chondrosarcoma typically affects adults between the age of 20 and 60 years old, and it is more common in men. The disease usually starts in the bones of the arms, legs or pelvis, but it can be found in any part of the body that contains cartilage. Sometimes chondrosarcoma grows on an otherwise healthy bone, and sometimes it grows on a benign bone tumor (an enchondroma or osteochondroma).
There are several types of chondrosarcoma that are named based on the way that they appear under the microscope. These include:
Clear cell chondrosarcoma
Dermatofibrosarcoma Protuberans (DFSP) is a rare type of cancer, a soft tissue sarcoma that develops in the deep layers of skin. It is sometimes described as having tentacles that can grow into surrounding fat, muscle and even bone. DFSP is most commonly found on the torso, but can also be seen on the arms, legs, head and neck. It has a tendency to recur in the same location after it is removed. However, it only spreads to other parts of the body in about 5% of cases.
DFSP most often starts as a small, firm patch of skin, approximately one to five centimeters in diameter. The skin is occasionally flat or depressed. It can be purplish, reddish or flesh-colored. The tumor typically grows very slowly (over months to years) and can become a raised nodule.
DFSP tends to affect people between the age of 20 and 50, but it has been diagnosed in people of all ages. There are about 1,000 cases diagnosed in the United States each year, with an incidence of about 1-5 people per million. The tumors affect black patients about twice as much as white patients.
Desmoplastic small round cell tumor (DSRCT) is an aggressive malignant neoplasm that occurs in adolescents and young adults. This tumor can co-express epithelial, neuronal, and mesenchymal markers. Clinical manifestations are often related to widespread abdominal disease. Distant metastases can be present at the time of diagnosis. The molecular hallmark of DSCRT is the EWS-WT1 fusion protein. The t(11;22)(p13;q12) translocation fuses the N-terminal domain of EWS to the C-terminal DNA-binding domain of WT1 resulting in an aberrant transcription factor involved in the pathogenesis of DSRCT. Despite intensive therapy, including surgery, radiotherapy and chemotherapy with or without stem cell transplantation, the 5-year survival continues to be less than 15%. New therapeutic approaches include molecularly targeted therapies and immunotherapy; the role of these modalities is yet to be defined.
Epithelioid sarcoma is a rare soft tissue sarcoma in young adults (20-39 year olds) involving the upper extremities 60% of the time. The name was given by Enzinger in 1970 to a group of soft tissue sarcomas that were confused with a variety of malignant and benign conditions, especially granulomatous process, synovial sarcoma and ulcerating squamous cell carcinoma.1 There is a “proximal type” variant first described in 1997 (see sidebar in Histology section).
This article will focus on conventional “distal” epithelioid sarcoma. Epithelioid sarcoma is a slow growing tumor with a high rate of recurrence and metastasis. Slow growth of the tumor, paucity of symptoms, benign appearance in early stage imaging studies, and indistinctive pathologic findings in some cases makes the diagnosis of epithelioid sarcoma challenging. The rarity of the disease also makes performing large controlled clinical trials to evaluate different treatment options almost impossible. This article reviews the epidemiology, clinical and pathological features, diagnosis, treatment and prognostic factors in patients with epithelioid sarcoma.
Fibrosarcoma of bone is a rare primary malignancy. It shares imaging and clinical features with several other bone pathologies. Fibrosarcoma shares histological features with other bone tumors and often cannot be distinguished from such lesions other than by an experienced musculoskeletal pathologist. Similarly, it is histologically indistinguishable from its soft tissue counterpart but has a significantly different incidence pattern and clinical profile. Treatment and prognosis are similar to other sarcomas of bone. Surgical extirpation is central to control of local disease. Given the rarity of fibrosarcoma of bone, large trials of chemotherapeutic regimens have not been possible. There have been promising results reported though. The following review will discuss this rare malignancy.
Leiomyosarcoma is an aggressive soft tissue sarcoma derived from smooth muscle cells typically of uterine, gastrointestinal or soft tissue origin. Sarcomas are malignant tumors arising from mesenchymal cell lines. They comprise a heterogeneous group of cancers, each with unique clinical, histologic, and radiographic characteristics. Soft tissue sarcomas account for 0.7% of malignancies. Sarcomas are generally classified according to the normal cell line that they most closely resemble. Of all soft tissue sarcomas, approximately 5-10% are leiomyosarcomas.1 Leiomyosarcoma of soft tissue is thought to arise from the smooth muscle cells lining small blood vessels. Leiomyosarcoma can also arise directly from the viscera, including the gastrointestinal tract and uterus.
Leiomyosarcoma of soft tissue is discussed in this article, while the companion article (linked in the above panel) addresses the uterine form of this disease. Gastrointestinal lesions are not included in this discussion. Primary leiomyosarcoma of bone is a distinct entity which is quite rare. While histologically similar, soft tissue leiomyosarcoma has classically been subdivided into three groups for prognostic and treatment purposes: leiomyosarcoma of somatic soft tissue, cutaneous leiomyosarcoma and leiomyosarcoma of vascular origin.4 A group of patients with leiomyosarcoma in the setting of immune dysfunction is also being discovered.5 Leiomyosarcomas are aggressive tumors that are often difficult to treat. The prognosis is poor, with survival rates among the lowest of all soft tissue sarcomas.
Liposarcoma is a rare cancer of connective tissues that resemble fat cells under a microscope. It accounts for up to 18% of all soft tissue sarcomas. Liposarcoma can occur in almost any part of the body, but more than half of liposarcoma cases involve the thigh, and up to a third involve the abdominal cavity.
Liposarcoma tends to affects adults between the ages of 40 and 60. When it does occur in children, it is usually during the teenage years.
There are four types of liposarcoma, each with its own unique characteristics and behaviors.
Well-differentiated liposarcoma is the most common subtype and usually starts as a low grade tumor. Low grade tumor cells look much like normal fat cells under the microscope and tend to grow and change slowly.
Myxoid liposarcoma is an intermediate to high grade tumor. Its cells look less normal under the microscope and may have a high grade component.
Pleomorphic liposarcoma is the rarest subtype and is a high grade tumor with cells that look very different from normal cells.
Dedifferentiated liposarcoma occurs when a low grade tumor changes, and the newer cells in the tumor are high grade.
The risk of recurrence and metastasis with liposarcoma increases with higher grade.
Mesenchymal chondrosarcoma is a malignant type of chondrosarcoma, or cancer of cartilage. Approximately two thirds of cases of mesenchymal chondrosarcoma occur in bone while the rest occur in places outside of the bone—i.e., in extra-skeletal locations. Unlike other types of malignant chondrosarcoma, which have a tendency to grow more slowly and rarely develop metastases, mesenchymal chondrosarcoma is a fast growing tumor that spreads more often. At the same time, it can remain dormant for long periods of time. It tends to affect children and young adults, but is a rare tumor, accounting for less than 1% of all sarcomas (Weis and Huvos).
Mesenchymal chondrosarcoma is thought to originate from cartilage precursor cells, or chondroblasts, that have failed to develop into mature chondrocytes. Chondrocytes are the cells found in normal cartilage. The designation “mesenchymal” refers to the appearance of the tumor cells as primitive looking connective tissue cells.
Malignant peripheral nerve sheath tumors (MPNSTs) are sarcomas which originate from peripheral nerves or from cells associated with the nerve sheath, such as Schwann cells, perineural cells, or fibroblasts. Because MPNSTs can arise from multiple cell types, the overall appearance can vary greatly from one case to the next. This can make diagnosis and classification somewhat difficult. In general, a sarcoma arising from a peripheral nerve or a neurofibroma is considered to be a MPNST. The term MPNST replaces a number of previously used names including malignant schwannoma, neurofibrosarcoma, and neurogenic sarcoma.
A sarcoma is defined as a MPNST when at least one of the following criteria is met:
It arises from a peripheral nerve
It arises from a preexisting benign nerve sheath tumor (neurofibroma)
It demonstrates Schwann cell differentiation on histologic examination.
Radiation-induced soft tissue sarcomas (RIS) are rare clinical entities. Their incidence increases as survival after radiotherapy improves, and they often constitute a therapeutic challenge. RIS generally develop with a median latency period of 10 years and encompass different histological types. The majority of RIS are high-grade and deep tumors. Large size and positive histologic margins after surgery are responsible for high local relapse rates and short survival. Surgery remains the primary treatment option for localized disease and often requires an aggressive approach. This article provides an overview of the clinical manifestations, prognosis, imaging and treatment of RIS.
Malignant fibrous histiocytoma (MFH), a type of sarcoma, is a malignant neoplasm of uncertain origin that arises both in soft tissue and bone. It was first introduced in 1961 by Kauffman and Stout and controversy has plagued it since. They described MFH as a tumor rich in histiocytes with a storiform growth pattern. By 1977, MFH was considered the most common soft tissue sarcoma of adult life. Despite the frequency of diagnosis, MFH has remained an enigma. No true cell of origin has ever been identified. In 2002, the World Health Organization (WHO) declassified MFH as a formal diagnostic entity and renamed it as an undifferentiated pleomorphic sarcoma not otherwise specified, NOS. This new terminology has been supported by a compelling body of evidence over the last decade to suggest that MFH represents a final common pathway in tumors that undergo progression towards undifferentiation. While it remains unclear how to most accurately organize these tumors, the term malignant fibrous histiocytoma represents the diagnosis for thousands of patients and is still commonly used by both patients and physicians. This review will describe soft tissue tumors once diagnosed as MFH.
Malignant fibrous histiocytoma (MFH), a type of sarcoma, is a malignant neoplasm of uncertain origin that arises both in soft tissue and bone. It was first introduced in 1961 by Kauffman and Stout and controversy has plagued it since. They described MFH as a tumor rich in histiocytes with a storiform growth pattern. By 1977, MFH was considered the most common soft tissue sarcoma of adult life. Despite the frequency of diagnosis, MFH has remained an enigma. No true cell of origin has ever been identified. In 2002, the World Health Organization (WHO) declassified MFH as a formal diagnostic entity and renamed it as an undifferentiated pleomorphic sarcoma not otherwise specified, NOS. This new terminology has been supported by a compelling body of evidence over the last decade to suggest that MFH represents a final common pathway in tumors that undergo progression towards undifferentiation. While it remains unclear how to most accurately organize these tumors, the term malignant fibrous histiocytoma represents the diagnosis for thousands of patients and is still commonly used by both patients and physicians.
There are two kinds of muscle cells in the body: smooth muscle cells and skeletal muscle cells. Smooth muscles control involuntary activities; skeletal muscles control voluntary activities. Rhabdomyosarcoma (RMS) is a malignant tumor (“cancer”) that arises from a normal skeletal muscle cell. Not very much is known about why normal skeletal muscle cells become cancerous. Because skeletal muscle cells are found in virtually every site of the body, RMS can develop in almost any part of the body.
Synovial sarcoma is a type of soft-tissue sarcoma. It is a rare cancer. Only about 1 to 3 individuals in a million people are diagnosed with this disease each year. It can occur at any age, but it is more common among teenagers and young adults. Synovial sarcoma seems to have a slight preference for males, with 12 male patients for every 10 female patients.
Despite its name, synovial sarcoma is not related to the synovial tissues that are a part of the joints. The disease starts most commonly in the legs or arms, but it can appear in any part of the body. On a pathology report, synovial sarcoma may be classified in different subtypes depending on what it looks like under the microscope or what specific gene mutation is involved. Synovial sarcoma is a high grade tumor. It spreads to distant sites in up to 50% of cases.
National Institutes of Health; National Cancer Institute
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