[Undifferentiated small cell tumor of the thoracopulmonary region].

The group of rounded small-cell tumors include different neoplasias involving different therapies; we can name neuroblastoma, Ewing' sarcoma, embrionary rhabdomyosarcoma, lymphoma and other pathology such as Askin's tumor or small cell tumor of the thorax area. Based on microscopic and immunohistochemistry findings, it is suggested that it originates from the neural crest or pluri-potential cells from the neuroectodermy. This has a very aggressive behaviour and is usually resistant to oncologic therapies.