Location pattern of recurrence of fully resected grade 1 meningiomas

Objective Meningiomas can lead to significant morbidity and mortality and have recurrence potential. While previous studies have focused on calculating recurrence risk, the precise location of the recurrence has not been delineated. This study aimed to investigate the spatial clustering pattern of recurrence relative to the original surgical bed for surgically treated Simpson Grade I-III, WHO Grade 1 meningiomas. Methods Patients diagnosed with grade 1 meningiomas and treated with surgical resection with subsequent recurrence were reviewed. Patient demographics, clinical outcomes, and radiographic characteristics were collected. Radiological images were analyzed to determine the location of recurrence relative to the initial tumor. We characterized recurrence as type A (within the surgical bed), type B (outside of the surgical bed, within 1 cm from the site), and type C (distal ≥ 1 cm of the resection site). Results Forty-two cases met the inclusion criteria. Twelve patients (29%) were male, and 30 (71%) were female. Median age at first treatment was 47 years, with 5.2 ± 3.4 years until recurrence. Recurrence rate was 54.7% at 5 years and 90.4% at 10 years. Twenty-eight patients (66.7%) had a type A recurrence, 11 (26.1%) had a type B recurrence, and 3 (7.1%) had a type C recurrence. Conclusions Our series demonstrates that while lesions often recur within the original lesion site, a significant portion recurs beyond the surgical bed. This highlights the substantial possibility of recurrence outside the resection cavity for fully excised benign meningiomas, which may aid in understanding disease progression and in guiding adjuvant therapy.