Giant nondural-based cauda equina meningioma with multiple cysts.

A very rare case of a giant nondural-based cauda equina meningioma with multiple cysts was presented. Spinal meningioma most commonly occurs in the thoracic or cervical region and typically adheres to the dura. Only six cases of nondural-based meningioma have been reported in English literature. All occurred in the cauda equina region. These patients were predominantly female and younger than those with typical intraspinal meningioma.A 46-year-old woman had a 4-year history of lower back pain and right leg pain. Progressive weakness of both lower extremities occurred. Magnetic resonance imaging revealed a giant cauda equina tumor with multiple cysts from T(12) to L(4). Following laminectomies from T(11) to L(5) and intradural exposure, the tumor was found to be draped loosely by the roots of the cauda equina and attached to a root without any firm connection with dura mater. Complete removal of the tumor was achieved after microdissection of arachnoid and sacrifice of an involved rootlet of the cauda equina. The appearance of tumor was that of a typical neurilemmoma. However, histological and immunohistochemical analyses were consistent with meningioma. Nondural-based intraspinal meningiomas are very rare, particularly a giant tumor with multiple cysts as our presenting case. All of the cases previously reported, including our case, have been located in the cauda equina region. Most of the patients were female and were young, suggesting that the nondural-based cauda equina meningiomas are age- and sex-related. An accurate preoperative and operative diagnosis are difficult. Care must be taken in the management of cauda equina tumors resembling neurilemmoma which may in fact represent meningioma, particularly in the younger female.