The incidence of multiple meningiomas--do solitary meningiomas exist?

Since the advent of computed tomography (CT) the recognition of the occurrence of multiple intracranial meningiomas (MIM) in the same individual has been on the increase. In our material the incidence of MIM at first assessment of CT films was 20%, with distant multiplicity prevailing over the regional one. This incidence will probably change in the course of time as MIM develop not only concurrently but also consecutively. On the other hand our surgical macroscopic incidence of regional multiplicity alone was 49%. The discrepancy between the CT and surgical findings prompted us to reevaluate the CT studies of 100 consecutive patients. This reevaluation demonstrated: 1. in two cases, small meningiomas were overlooked at first assessment; 2. nineteen cases of solitary globoid meningiomas seemed to be the consequence of the coalescence of adjacent smaller masses. Thus, the CT incidence of MIM increased to 40%, with regional multiplicity prevailing over the distant one. The authors think that the aforesaid findings question the very existence of solitary meningiomas as a pathological entity. They would be the end product of a coalescence of multiple adjacent smaller growths. Accordingly, a more aggressive surgical approach is suggested to include the resection of a generous fringe of dura mater around the main tumour. As this is not always possible, or too risky, a comprehensive complement to surgery like radiotherapy could be given a reasonable randomized trial.