Epithelioid sarcoma (ES) is a rare and aggressive soft tissue cancer that primarily affects young adults and adolescents. It commonly arises in the extremities, such as hands, forearms, and lower limbs, though it can develop in other parts of the body. Characterized by slow-growing nodules, this malignancy often mimics benign conditions, leading to delayed diagnosis and treatment.
Types of Epithelioid Sarcoma
There are two main subtypes of epithelioid sarcoma:
- Distal-Type Epithelioid Sarcoma: The classic form, often affecting the hands and forearms.
- Proximal-Type Epithelioid Sarcoma: More aggressive, commonly occurring in deep tissues of the pelvis, trunk, and head and neck region.
graph TD;
A[Soft Tissue Sarcoma] -->|Subtype| B[Epithelioid Sarcoma];
B -->|Classic| C[Distal-Type];
B -->|Aggressive| D[Proximal-Type];Causes and Risk Factors
The exact cause of epithelioid sarcoma remains unknown, though genetic mutations play a crucial role. The loss of SMARCB1/INI1 gene function is a hallmark of this cancer, leading to uncontrolled cellular growth.
Risk Factors:
- Genetic predisposition
- Previous radiation therapy
- Chronic tissue irritation or trauma (though not conclusively proven)
Symptoms of Epithelioid Sarcoma
Early symptoms may be subtle, contributing to late diagnosis. Common symptoms include:
- Painless lumps or nodules in the extremities
- Slow-growing masses that may ulcerate
- Swelling and tenderness in affected areas
- Limited mobility if near joints
- Skin breakdown or open wounds in advanced stages
Diagnosis and Staging
Diagnostic Procedures:
- Physical Examination: Assessment of lumps, mobility, and skin changes
- Imaging Tests: MRI, CT scans, and PET scans help determine tumor size and spread
- Biopsy: Fine-needle aspiration or excisional biopsy confirms malignancy
- Immunohistochemistry: Staining for INI1 protein loss to verify diagnosis
Treatment Options for Epithelioid Sarcoma
Surgical Intervention
Surgical excision with wide margins is the primary treatment to prevent recurrence. Amputation may be necessary in severe cases.
Radiation Therapy
Radiotherapy is used post-surgery to eliminate residual cancer cells and reduce recurrence risks, especially in inoperable cases.
Chemotherapy
Though not highly effective, chemotherapy is used in metastatic or advanced cases. Common drugs include doxorubicin and ifosfamide.
Targeted Therapy
Tazemetostat, an EZH2 inhibitor, is approved for INI1-deficient epithelioid sarcoma and offers a targeted approach with fewer side effects.
Prognosis and Survival Rates
Prognosis depends on tumor stage, size, and metastasis:
- Localized disease: 5-year survival rate of 70-80%
- Lymph node involvement: 5-year survival rate of 50%
- Distant metastases: 5-year survival rate of <20%
