Clear cell sarcoma

Clear-cell sarcoma
Clear cell sarcoma. Tumor cells with prominent nucleoli and clear cytoplasm are arranged in well-defined nests surrounded by dense fibrous stroma.
Classification and external resources
ICD-O	9044/3
MeSH	D018227
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Clear-cell sarcoma (formerly known as malignant melanoma of the soft parts) is a rare form of cancer called sarcoma. 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.

It has been associated with both EWSR1-ATF1 and EWSR1-CREB1 fusion transcripts.

Clear cell sarcoma of the soft tissues in adults is not related to the pediatric tumor known as clear cell sarcoma of the kidney.

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, epithelioid and tumor giant cells. Approximately two thirds of the tumors contain melanin pigment. Clear cell sarcoma, similar to melanoma, has consistent positivity for S-100, HMB-45, and MITF.

Imaging studies such as X-rays, computed tomography scans, or MRI may be required to diagnose clear-cell sarcoma together with a physical exam. Normally a biopsy 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.

It presents as a slow growing mass that especially affects tendons and aponeuroses and it is deeply situated. Patients often perceive it as a lump 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. Patients diagnosed with clear cell sarcoma are usually between the ages of 20 and 40.

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