Epithelioid sarcoma overview

# Overview
Epithelioid sarcoma is a rare mesenchymal soft tissue tumor. It often occurs in the extremities of young people.  Diagnosis is often delayed because of the unusual nature of the tumor. Epithelioid sarcoma was first discovered by Dr. J. Laskowski, a polish doctor, in 1961 following the description of a clinical entity called sarcoma aponeuroticum due to the involvement of aponeurosis. Enzinger coined the term epithelioid sarcoma in 1970. Mutations in the SMARCB1 gene cause epithelioid sarcoma. Epithelioid sarcoma must be differentiated from synovial sarcoma, wart, ganglion cyst, rhabdomyosarcoma, and clear cell sarcoma. Irregular (or nodular) lesions below the skin surface are the major symptom of epithelioid sarcoma. The symptoms of epithelioid sarcoma usually develop in the second decade of life and start with symptoms such as mass. Epitheliod sarcoma has a tendency for lymph node metastasis. The most common sites of epithelioid metastasis include lungs, lymph nodes, and scalp. Common complications of epithelioid sarcoma include metastasis, nerve compression, and numbness. The prognosis of epithelioid sarcoma is good for females. The predominant therapy for epithelioid sarcoma is surgical resection. Adjunctive chemotherapy, radiation, and chemoradiation may be required.

# Historical Perspective
Epithelioid sarcoma was first discovered by Dr. J. Laskowski, a polish doctor, in 1961 following the description of a clinical entity called sarcoma aponeuroticum due to the involvement of aponeurosis. Enzinger coined the term epithelioid sarcoma in 1970.

# Pathophysiology
Mutations in the SMARCB1 gene cause epithelioid sarcoma. On gross pathology, solid, multinodular mass, glistening gray tan appearance, and multiple areas of hemorrhage and necrosis are characteristic findings of epithelioid sarcoma. On microscopic histopathological analysis, central necrosis surrounded by bland, polygonal cells with eosinophilic cytoplasm and peripheral spindling, desmoplasia, focal calcification, or metaplastic ossification are characteristic findings of epithelioid sarcoma.

# Causes
Mutations in the SMARCB1 gene cause epithelioid sarcoma.

# Differentiating Epithelioid sarcoma from other Diseases
Epithelioid sarcoma must be differentiated from synovial sarcoma, wart, ganglion cysts, rhabdomyosarcoma, and clear cell sarcoma.

# Epidemiology and Demographics
The epithelioid sarcoma is a very rare disease. The incidence of epithelioid sarcoma increases between ages of 10 and 39 and the average age of presentation was 27 years.  Males are more commonly affected with epithelioid sarcoma than female. Epithelioid sarcoma of upper extremity usually affects individuals of the Caucasian race.

# Risk Factors
The most potent risk factor in the development of epithelioid sarcoma is the presence of family history of epithelioid sarcoma.

# Natural history, Complications and Prognosis
The symptoms of epithelioid sarcoma usually develop in the second decade of life and start with symptoms such as mass. Epithelioid sarcoma has a tendency to lymph node metastasis. The most common sites of epithelioid metastasis include lungs, lymph nodes, and scalp. Common complications of epithelioid sarcoma include metastasis, nerve compression, and numbness. The prognosis of epithelioid sarcoma is good for females.

# Staging
The staging for epithelioid sarcoma takes into account size and location of the primary tumor, lymph node involvement, presence and location of metastasis, and histologic grade.

# History and Symptoms
Irregular (or nodular) lesions below the skin surface are the major symptom of epithelioid sarcoma.

# Physical Examination
Patients with epithelioid sarcoma usually appear healthy. Physical examination of patients with epithelioid sarcoma is usually remarkable for a firm to hard palpable masses in the extremities.

# MRI
MRI may be performed to detect metastases of epithelioid sarcoma to determine anatomic boundaries.

# Other Diagnostic Studies
Other diagnostic studies for epithelioid sarcoma include genetic testing and immunohistochemistry.

# Biopsy
Tissue biopsy may be helpful in the diagnosis of epithelioid sarcoma. Findings on biopsy suggestive of epithelioid sarcoma include white nodules with infiltrating margins,  epithelial cells well blended with fusiform cells with intracytoplasmic vacuoles, and "pseudo granulomatous" proliferation of cells around acellular necrotic debris.

# Medical Therapy
The predominant therapy for epithelioid sarcoma is surgical resection. Adjunctive chemotherapy, radiation, and chemoradiation may be required.

# Surgery
Surgery is the mainstay of treatment for epithelioid sarcoma.