Postoperative imaging and long-term surveillance in ossified spinal meningiomas

Dear Editor, The recently published case series by Mrimba et al1, entitled “Ossified spinal psammomatous meningioma: surgical outcomes and literature review,” represents a noteworthy contribution to the limited body of literature addressing this rare and technically demanding intradural–extramedullary meningioma subtype. The authors are to be commended for their meticulous radiological documentation, clear operative descriptions, and thoughtful synthesis of early postoperative outcomes in three patients with thoracic ossified psammomatous meningiomas. This correspondence is prepared in accordance with the TITAN 2025 Guidelines for AI transparency2. All content has been verified by the author. While the report provides valuable clinical insights, we respectfully wish to expand upon one aspect that we believe merits further clarification – namely, the interpretation of postoperative follow-up duration in relation to tumor recurrence. The authors report an absence of residual or recurrent tumor at 3–6 months postoperatively and suggest that a follow-up interval of 6 months to 1 year is adequate for assessing recurrence. We submit that, although the authors’ early radiological observations are accurate, such short-term follow-up should not be construed as evidence of long-term tumor control, given the established natural history of spinal meningiomas. Recurrence in spinal meningiomas is a long-term phenomenon Extensive studies – including large historical cohorts and modern institutional series – demonstrate that recurrence in WHO grade I spinal meningiomas typically manifests years to decades after the initial operation. Reported recurrence rates of 4–10% often become evident beyond 5–10 years, not during the first postoperative months3–5. The classical monograph by Cushing and Eisenhardt6 first highlighted the prolonged biological course of spinal meningiomas, and subsequent data confirm late recurrences, including those occurring 8–15 years after resection3,4. Exceptional cases have been documented even 18 years postoperatively7. These findings underscore that 3–6 months of follow-up is insufficient to meaningfully characterize recurrence risk in these indolent tumors. Ossified variants particularly warrant extended surveillance Heavily calcified and ossified meningiomas may present additional challenges during microsurgical dissection, including firmer dural attachment and indistinct tumor–arachnoid planes. Long-term MRI surveillance – typically annual imaging for at least 5 years, followed by periodic reassessment – is recommended in reviews of ossified and calcified variants due to the potential for subtle residual dural involvement that may remain dormant for extended periods8. Extent of dural resection influences recurrence Recurrence is also influenced by dural management and Simpson grade3,9. As the authors did not report Simpson grading or specify the extent of dural excision versus coagulation, the long-term recurrence profile for the presented cases cannot be fully contextualized, further reinforcing the importance of prolonged follow-up. Recommendation To enhance interpretability for readers, we respectfully propose rephrasing the findings as “no early radiological evidence of residual or recurrence at 6 months,” which accurately reflects the postoperative interval studied while aligning with established evidence on long-term outcomes. This distinction is essential in the context of slow-growing WHO grade I tumors, in which recurrence may not become apparent for many years. The work of Mrimba et al provides a valuable contribution to the literature on ossified spinal meningiomas. Our comments aim to complement their efforts by highlighting the necessity of long-term surveillance in accurately assessing recurrence patterns in these rare lesions. Ethical approval Not applicable. Consent Not applicable.