ABSTRACT
Malignant schwannoma is a relatively rare malignant neoplasm arising from schwann cell of neuroectodermal origin that infiltrate locally and widely, and metastases. Inreaosseous bone involvement or retroperitoneal location of this tumor is extremely rare. A rare case of solitary malignant schwannoma which originated in the sacrum and extended to the retroperitoneal space in a 34 year-old male without neurofibromatosis reported. Simple X-ray showed not sclerotic, smooth marginated lytic defect in the right sacral bone. Computed tomography(CT) of sacrum revealed homogenous soft mass with intraosseous and dumbel shaped retroperitoneal extension without enhancement after were appeared in serial iliac artery angiogram. We could remove the tumor mass without specific technical difficulty with the help of CT and angiographic findings.