Clear cell sarcoma is a rare form of

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

called a

sarcoma A sarcoma is a malignant tumor, a type of cancer that arises from transformed cells of mesenchymal ( connective tissue) origin. Connective tissue is a broad term that includes bone, cartilage, fat, vascular, or hematopoietic tissues, and sar ...

. It is known to occur mainly in the soft tissues and dermis. Rare forms were thought to occur in the gastrointestinal tract before they were discovered to be different and redesignated as GNET. Recurrence is common. Clear cell sarcoma's neoplastic cells express the ''EWSR1-ATF1'' fusion gene in a majority of cases or a ''EWSR1-CREB1'', ''EWSR1-CREM'', or ''EWSR1-DDIT3'' fusion gene in a small subset of cases (see FET gene family of fusion genes). Clear cell sarcoma of the soft tissues in adults is not related to the pediatric tumor known as clear cell sarcoma of the kidney.

Signs and symptoms

It presents as a slow growing mass that especially affects

tendons A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

and

aponeuroses An aponeurosis (; plural: ''aponeuroses'') is a type or a variant of the deep fascia, in the form of a sheet of pearly-white fibrous tissue that attaches sheet-like muscles needing a wide area of attachment. Their primary function is to join muscl ...

and it is deeply situated. Patients often perceive it as a

lump Lump may refer to: * "Lump" (song), a 1995 song by The Presidents of the United States of America * ''Lump'' (compilation album), a 2000 best-of album by The Presidents of the United States of America * Lump (dog), a dog who inspired Pablo Pica ...

or hard mass. It causes either pain or tenderness but only until it becomes large enough. This kind of tumor is commonly found in the extremities especially around the knee, feet and

ankle The ankle, or the talocrural region, or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular joi ...

. Patients diagnosed with clear cell sarcoma are usually between the ages of 20 and 40.

Pathology

Despite the name clear cell sarcoma, the tumor cells do not necessarily need to have clear cytoplasm. The lesion has a distinctly nested growth pattern with a mixture of

spindle Spindle may refer to: Textiles and manufacturing * Spindle (textiles), a straight spike to spin fibers into yarn * Spindle (tool), a rotating axis of a machine tool Biology * Common spindle and other species of shrubs and trees in genus ''Euony ...

, epithelioid and

tumor giant cell A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

s. Approximately two thirds of the tumors contain melanin pigment. Clear cell sarcoma, similar to melanoma, has consistent positivity for S-100,

HMB-45 HMB-45 is a monoclonal antibody that reacts against an antigen present in melanocyte, melanocytic tumors such as melanomas, and stands for Human Melanoma Black. It is used in anatomic pathology as a marker for such tumors. The specific antigen reco ...

, and

MITF Microphthalmia-associated transcription factor also known as class E basic helix-loop-helix protein 32 or bHLHe32 is a protein that in humans is encoded by the ''MITF'' gene. MITF is a basic helix-loop-helix leucine zipper transcription factor ...

Diagnosis

Imaging studies such as

X-rays An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nbs ...

, computed tomography scans, or

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...

may be required to diagnose clear-cell sarcoma together with a physical exam. Normally a

biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a dise ...

is also necessary. Furthermore, a chest CT, a bone scan and positron emission tomography (PET) may be part of the tests in order to evaluate areas where metastases occur.

Treatment

Treatment depends upon the site and the extent of the disease. Clear cell sarcoma is usually treated with surgery in the first place in order to remove the tumor. The surgical procedure is then followed by radiation and sometimes

chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemothe ...

. Few cases of clear cell sarcoma respond to

. Several types of

targeted therapy Targeted therapy or molecularly targeted therapy is one of the major modalities of medical treatment ( pharmacotherapy) for cancer, others being hormonal therapy and cytotoxic chemotherapy. As a form of molecular medicine, targeted therapy blocks ...

that may be of benefit to clear cell sarcoma people are currently under investigation.

Prognosis

When the tumor is large and there is presence of necrosis and local recurrence, the prognosis is poor. Presence of metastasis occurs in more than 50% cases and the common places of its occurrence are the

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

, lymph node and

lungs The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side ...

. Five-year survival rates, which are reported to be between 50 and 65%, can be misleading because the disease is prone to late metastasis or recurrence. Ten and twenty-year survival rates are 33% and 10%, respectively.

References

External links

{{Soft tissue tumors and sarcomas Melanoma Soft tissue tumor