Meningiomas are the most common primary intracranial tumors, and most remain asymptomatic throughout the patient’s life.
The routine use of CT & MRI for numerous indications inevitably results in the discovery of incidental (asymptomatic) meningiomas. In a population-based study (the study population was middle-class Caucasians and result, may not be generalizable to other groups), incidental meningiomas were seen in 0.9% of MRIs. In another series, 32% of primary brain tumors seen in imaging studies were meningiomas, and 39% of these were asymptomatic.
Of 63 cases followed for > 1 year with nonsurgical management, 68% showed no increase in size over an average follow-up of 36.6 mos, whereas 32% increased in size over 28 mos average follow-up.
Asymptomatic meningiomas with calcification seen on CT and/or hypointensity on T2WI MRI appeared to have a slower growth rate.
Data are lacking to make evidence-based management guidelines. A suggestion is to obtain a follow-up imaging study 3–4 months after the initial study to rule out rapid progression, and then repeat annually for 2–3 years. The development of symptoms would prompt performing a study at that time. Treatment is indicated for lesions that produce symptoms that cannot be satisfactorily controlled medically, or for those that demonstrate significant continued growth on serial imaging studies. When surgery was performed, the perioperative morbidity rate was statistically significantly higher in patients > 70 years old (23%) than in those < 70 (3.5%).
Asymptomatic intracranial meningioma is a benign disease; however, nearly two-thirds of patients experience tumor growth and one-third of untreated patients eventually require neurosurgical interventions during watchful waiting 1).
In the series of Jadid et al., long-term tumour growth of incidentally detected asymptomatic meningiomas appeared to be much higher than expected. This information needs to be considered when discussing surgery, since the indication for surgery may be stronger than previously stated, especially for younger patients with tumours that can be reached at low risk 2).
Niiro et al., stated that in elderly patients with asymptomatic meningiomas, careful clinical follow up with imaging studies is important. The imaging features mentioned in his article may contribute to prediction of tumour growth 3).
For Yoneoka et al., clinical and radiological observations would be advisable for these patients (especially young patients and patients with a large tumour), in view of the presence of rapidly growing tumours in some of the patients 4).
Hashimoto et al., observed that Skull base incidental meningiomas (IDM) tend not to grow, which is different from non-skull base tumors. Even when IDMs grow, the rate of growth is significantly lower than that of non-skull base tumors. The same conclusion with regard to biological behavior was confirmed in symptomatic cases based on MIB-1 index analyses. This findings may impact the understanding of the incidental intracranial meningioma natural history, as well as strategies for management and treatment of IDMs and symptomatic meningiomas 5).