A significant portion of my practice involves the evaluation of soft tissue masses. The may be found in the forefoot, heel, ankle or lower leg. Majority of the lesions that I encounter are benign which means non-threatening or assumed to be harmless.
Not too long ago, a patient presented to my office with a rapidly growing mass of the forefoot. The mass appeared and grew within a 6 month span. The patient had gone to see another physician who was injecting an alcohol solution into the mass to stop it's growth. The injections did not help and the mass continued to grow, pushing the involved and bones and soft tissue out of the way.
A MRI stated that there was a vascular (having a blood supply) tumor which was heterogeneous (not uniform in structure) in nature.Due to the rare nature of the mass, it was sent to a Pathology specialist. The diagnosis was Clear Cell Sarcoma which is an extremely rare form of malignant cancer.
Clear cell sarcoma (formerly known as malignant melanoma of the soft parts) is a rare type of cancer which usually affects 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.
Recurrence is common.
Signs and Symptoms:
A slow growing, hard, deep lying mass that is usually painless until it grows very large. Clear Cell Sarcoma is usually found in the extremities and has a predilection for the knees, ankles and feet. The Sarcoma usually present in patients aged 20-40 and is equal amongst the genders.
Diagnosis is determined by physical examination in conjunction with X-rays, CT (Computed Tomograpy Scans), MRI (Magnetic Resonance Scans). In addition, a biopsy of the mass is extremely beneficial. If suspicion of metastasis, is suspected, A chest CT, bone scan or PET (Positive Emission Tomography) may be ordered.
In situations where the tumor is large in size and there is recurrence and associated necrosis, the prognosis may be poor. The key factor in prognosis is the metastasis (travel from site of origin to another part of the body). The most common sites metastasis is the bone, lungs and lymph nodes.
Survival rates at 5 years have been reported to be about 54% . Ten and twenty-year survival rates are about 30% and 10%.
When viewed under a microscope, these tumors show some similarities to traditional skin melanomas,  Characteristically, they have solid nests and fascicles of tumor cells with clear cytoplasm and prominent nucleoli. . The clear cell sarcoma has a uniform and distinctive morphological pattern which makes it distinguishable from other types of sarcoma.
Treatment of Cell Cell Sarcoma varies depending upon the location and the extent of the disease. Surgery is the first plan of action to remove the tumor. I would recommend the tumor be sent to Pathology. Radiation and in some cases, chemotherapy follows the surgery. Chemotherapy may or may not be initiated due to only a few cases responding effectively to Chemotherapy.
 The Doctor's Doctor
,  Atlas of Genetics and Cytogenetics in Oncology and Haematology