An epithelioid sarcoma (ES) is a rare form of cancer arising from epithelial cells (the tissue covering all organs). ES constitutes less than 1% of all primary soft tissue sarcomas and basically of two types. The traditional form (distal-type) is most common in adolescents and young adults and large cell (proximal-type) epithelioid sarcoma is a less common form that tends to be more aggressive and primarily affects adults. It has been reported to occur in the chest wall, limb, brain, and other visceral areas and has a high rate of recurrence. Chest walls are among the most vulnerable organs to develop ES. This is primarily seen in children and adolescents.
What are the types and symptoms of ES?
ES in the chest wall can be classified into 4 subtypes based on the site of its origin:
Each subtype causes different symptoms depending on their location and severity. Some possible symptoms are listed below:
Painless nodules on bones
Large masses in the chest cavity (angioedema)
Prolonged chest pain due to chest wall deformities or an expansion of the affected area beyond its normal size
Sharp pain when it is touched on palpation in the case of advanced stage ES .
How ES in the chest wall can be diagnosed?
ES is characterized by aggressive behavior, including a high recurrence rate and regional lymph node metastases. This type of sarcoma can arise from gene mutations that help maintain normal cell differentiation and development. An epithelioid sarcoma of the chest wall may be mistaken for breast cancer in ultrasound and radiology. For the diagnosis of ES of the chest wall, conventional diagnostic methods like X-ray, computed tomography (CT), and magnetic resonance imaging (MRI) are not helpful, because CT or MRI findings regarding this disease are nonspecific. ES may appear as a slight enlargement of the chest wall’s right upper or lower part on a chest x-ray or CT scan. A high-resolution chest radiograph (HRCT) with contrast will be used to identify solid masses, characteristic calcification in some cases, and/or adhesion fibrosis. To rule out other causes, such as lymphocele and pleural effusion, computed tomography (CT) should be performed if clinically suspected. A correct diagnosis cannot be made until immunohistochemistry is done. Sentinel lymph node biopsy may be considered in ES patients for histopathological confirmation . Loss of integrase function is the most common alteration found in almost 90% of ES cases. Integrase is an enzyme that helps in the regulation of the replication process. Its functional loss leads to the deregulation of targeted genes, uncontrolled cellular growth, and neoplastic transformation. An immunohistochemistry test for integrase should be used to confirm the diagnosis of ES. Additionally, ES cells secret biomarkers into the blood, which can be used as a diagnostic tool. While doing immunohistochemistry, care should be taken to rule out the differential diagnosis of fibrohistiocytic sarcoma, liposarcoma, osteosarcoma, and neurogenic nephropathy.
Is there treatment for Epithelioid Sarcoma?
Epithelioid sarcoma of the chest wall is treated by wide surgical resection to prevent recurrences and reconstruction of the chest wall deficit. The goals of the reconstruction of the chest wall are adequate stability in respiration, water- and airtight closure, and an acceptable cosmetic appearance. Muscle flap repair is well established and often involves the application of alloplastic and/or xenogeneic materials. Neoadjuvant therapy (either radiotherapy or chemotherapy) is often administered to reduce local relapses. Radiation therapy can be performed before, during, or after the surgery depending upon the severity of the condition. Patients with metastatic ES have a poor prognosis with an expected overall survival of about 1 year. In advanced cases of epithelioid sarcoma, doxorubicin-based regimens can be advised. Tazemetostat, a chemotherapeutic agent which inhibits the spread of cancer cells has shown promising results in ES patients where complete surgical removal of the tumor mass cannot be done .
The early the diagnosis the better the prognosis
ES chest wall tumors present a challenging problem for both the diagnosis and management of the disease. Surgical excision is curative, but the chest wall deficit needs to be reconstructed. Important prognostic factors are tumor size, tumor location, and deep extension into the pleura. The outcome of this sarcoma in the chest wall depends on the completeness of tumor resection and reoperation. These tumors have a very poor prognosis, especially if they progress to locally aggressive or metastatic disease. They should be removed as early as possible after the diagnosis to reduce damage to other structures, which will improve the prognosis of the disease and thereby the quality of life of patients.
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