Benign meningiomas (WHO Grade I) with atypical histological features: correlation of histopathological features with clinical outcomes.
OBJECT World Health Organization (WHO) Grade I (benign) meningiomas with atypical features may behave more aggressively than similarly graded tumors without atypical features. Here, the prognostic significance of atypical features in benign meningiomas was determined. METHODS Data from patients diagnosed with WHO Grade I benign meningiomas per the 2007 WHO criteria and who underwent surgery between 2002 and 2012 were retrospectively reviewed. Patients were stratified by the absence or presence of 1 to 2 atypical features with review of the clinical and histological factors. RESULTS A total of 148 patients met the inclusion criteria (n = 77 with atypia; n = 71 without atypia). The median follow-up duration after pathological diagnosis was 37.5 months. Thirty patients had progression/recurrence (P/R) after initial treatment, and 22 (73%) of 30 patients with P/R had 1-2 atypical features. The presence of atypical features was significantly associated with P/R (p = 0.03) and independent of the MIB-1 labeling index. The 1-year and 5-year actuarial rates of P/R were 9.6% versus 1.4% and 30.8% versus 13.8% fortumors with and without atypical features, respectively. Higher Simpson grade resection (II-IV vs I) was associated with the increased risk of P/R (p < 0.001). Stratification of patients into low-risk (Simpson Grade I), intermediate-risk (Simpson Grade II-IV with no atypical features), and high-risk groups (Simpson Grade II-IV with atypical features) was significantly correlated with increased risk of P/R (p < 0.001). CONCLUSIONS Patients with benign meningiomas with atypical features and those undergoing Simpson Grade II-IV resection are at significantly increased risk of P/R. Patients with these features may benefit from the consideration of additional surgery and/or radiation therapy.
Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, Baltimore, Maryland; and 
Ariel E
AE
Marciscano
Departments of 2 Pathology.
Anat O
AO
Stemmer-Rachamimov
Radiation Oncology.
Andrzej
A
Niemierko
Radiology, and.
Mykol
M
Larvie
Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts.
William T
WT
Curry
Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts.
Fred G
FG
Barker
Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts.
Robert L
RL
Martuza
Departments of 2 Pathology.
Declan
D
McGuone
Radiation Oncology.
Kevin S
KS
Oh
Radiation Oncology.
Jay S
JS
Loeffler
Radiation Oncology.
Helen A
HA
Shih
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003131:Combined Modality Therapy; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019394:Ki-67 Antigen; D008297:Male; D008579:Meningioma / Q000473:pathology* / Q000601:surgery / Q000628:therapy*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology; D019635:Neurosurgical Procedures; D011379:Prognosis; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D018570:Risk Assessment; D016896:Treatment Outcome; D014944:World Health Organization; D055815:Young Adult
D019394:Ki-67 Antigen
CI = confidence interval; HR = hazard ratio; N:C = nuclear:cytoplasmic; NF2 = neurofibromatosis Type 2; P/R = progression/recurrence; RT = radiotherapy; STR = subtotal resection; Simpson grade; WHO = World Health Organization; atypia; atypical; benign; histopathological; meningioma; oncology