Leioblastoma, developing as an hour-glass tumour of the spinal canal

The present paper describes a tumour that developed like an hour-glass tumour, both intraspinally at lumbar level and retroperitoneally. At operation the tumour was diagnosed as a malignant neurinoma. The structure of the tumour, studied by light and electron microscopy, as well as the subsequent evolution of the case, showed it to be a leiomyoblastoma with a retroperitoneal origin, that gradually infiltrated the nerve root (L1) up to the dura mater, epidural and subdural space, where it took on the appearance of a primary tumour of these formations. The author discusses the existence of the so-called primary intracranial rhabdomyosarcoma and its relationship with medullomyoblastoma.