Fluorescence-guided resection in bone and soft tissue infiltrating meningiomas.

Background: Bone infiltration of the tumour is common in meningioma surgery. This may also affect patients without indicative signs of bone infiltration on preoperative imaging. Unrecognized bone invasion may lead to higher recurrence rates. 5-ALA fluorescence-guided resection (5-ALA-fg) could be a promising tool to help recognize possible bone invasion and/or tumour remnants. However, there is still little data about 5-ALA-fg resection in bone and soft tissue infiltrating meningiomas.
Methods: We performed a retrospective study of 11 patients who were operated with the aid of 5-ALA due to bone and soft tissue infiltrating meningiomas at the University Hospital of St. Poelten between 2013 and 2019.
Results: Strong and homogeneous fluorescence of the meningioma was observed in 9 cases (81.8%) and vague and heterogeneous fluorescence in 2 cases (18.2%). Hyperostosis on computerized tomography was evident in 3 of 6 cases (50%) and bone infiltration was visible in preoperative magnetic resonance imaging in 7 of 11 patients (63.6%). All eleven patients showed positive fluorescence of the bone infiltrating part. In all 7 cases where tissue could be collected, histopathological testing verified tumour infiltration (100%). There was also fluorescence of the periosteum in 3 cases and histopathological testing verified tumour infiltration in 100%.
Conclusion: There is growing evidence that 5-ALA-fg resection can help to identify bone infiltration in meningioma surgery. Therefore, it may help to improve extent of resection. However, further studies are necessary to investigate the rate of false-negative fluorescence and its effect on progression free survival. If 5-ALA-fg resection of meningioma is performed, the attending surgeon should also consider investigating the adjacent periosteum under blue light for detection of possible fluorescence.