A primitive neuroectodermal tumor (small round blue cell tumor) of the thorax which can involve the periosteum, thoracic wall and/or pleura though it spares the lung parenchyma. The disease is MONDO_0006094 (Askin tumor). Also known as: Askin's tumor, Askin's tumour, PNET of thoracopulmonary region, peripheral neuroectodermal tumor of thoracopulmonary region, peripheral neuroectodermal tumour of thoracopulmonary region, small cell tumor of thoracopulmonary region, small cell tumour of thoracopulmonary region.