ABSTRACT
Malignant small round cell tumor (SRCT) of the thoracopulmonary region appears to originate in the soft tissues of the chest wall or the peripheral lung. A differential diagnosis of poorly differentiated small round cell tumors which include Ewing's sarcoma of bone and soft tissue, embryonal rhabdomyosarcoma, Askin tumor, neuroblastoma, peripheral neuroectodermal tumor, small cell osteogenic sarcoma and lymphoma are after difficult by light microscopy alone. In recent, by the extensive studies electron microscopic examination, histochemical study, immunochemical study, cytogenetics and gene analysis, these tumors may be derived from the primitive and pluripotential cells, differentiating into mesenchymal, epithelial and neural features in variable proportions. Treatment for SRCT of thoracopulmonary regin is not determined because of massive involvement of the lung, pleura or soft tissues of the chest wall resulted in a dismal outcome despite aggressive surgery, irradiation and chemotherapy.