Spinal meningiomas: Immunohistochemical expression of matrix metallo-proteinase-9 (MMP-9), hormone receptor status and surgical considerations

Spinal meningiomas (SMs) are rare and show an incidence of 10-15% of all meningiomas and of 20-25% of all spinal tumours. SMs occur more often in women usually between the ages of 40 and 70 years. They arise from mesothelial cell rest found where the arachnoid joins the dura of the nerve root sheaths, creating signs and symptoms of a dermatomal pattern. SMs are frequently located in the thoracic tract followed by cervical, and rarely, lumbo-sacral tracts. Traditional laminectomy for tumour resection may contribute to pain and instability. Consequently we have performed a less invasive surgical approach. In this study, we report a series of 58 spinal meningiomas surgically treated in our Department. In all cases we evaluated the immunohistochemical expression of estrogen (ER) and progesterone receptors (PR). In addition, in order to examine SMs lower biological aggressiveness we analyzed the immunohistochemical expression of MMP-9. The clinical history and the radiological findings were reviewed. All patients were surgical treated by minimally invasive laminectomy preserving arthicularis processes. Ultrasonic cavitation was adopted in many cases for debulking the tumour. Complete excision, including dura and bone (Simpson 1) had been achieved in 10/58 meningiomas (17%); complete excision with reliable coagulation of dural attachments (Simpson 2) had been performed in 37/58 (64%); complete excision of the solid tumour, but with insufficient dural coagulation or bone excision (Simpson 3) had been obtained in 11/58 (19%) of cases. Following histological revision, the SMs were classified as follow: 26 transitional, 8 meningothelial, 8 psammomatous, 7 metaplastic, 5 fibrous, 2 clear cells, 1 angiomatous and 1 atypical. No expression of ER was observed in all cases analyzed, whereby PR immune-expression was found in 86% of cases. A variable MMP-9 expression was evidenced in 73% of meningiomas. A positive significant correlation between MMP-9 and the percentage of PR expression was also observed. As MMP-9 seems to be involved in osteogenesis, we may hypothesize that MMP-9 high expression reflects the acquirement of metaplastic osteogenic properties by the neoplastic cells. With the advent of modern surgical techniques we can performa less demolitive monolateral laminotomy with possible controlateral vision, without iatrogenic instability, achieving reduced intraoperative bleeding with a general reduction of hospitalization and morbidity. None of our patients underwent fusion.