INTRODUCTION

Meningiomas in the pediatric population are similar in many ways to those in their adult counterparts, although several characteristics are unique to this group. These, including the lack of female predominance, larger size at presentation, as well as lack of dural attachments and unusual anatomic locations, are discussed in this chapter. Whereas intracranial meningioma is one of the most common tumors in adults, they are uncommon in children, accounting for only 2% to 4.2% of all pediatric tumors in most series.^1,2 As these lesions are relatively uncommon, they have created some controversies in particular with regard to their recurrence and long-term outcomes due to conclusions drawn on small series reported before modern imaging and surgical techniques. Nonetheless, many series reported recurrences even with totally resected tumors,³ which may imply the need for ongoing and life long follow-up. Many studies during the last 30 years have reported on this entity, which had been considered very rare in the past^1,4 (Table 47-1). These series also suggested a poor prognosis; however, inclusion of malignant meningeal tumors and patients with neurofibromatosis may be the explanation for this conclusion¹ (Tables 47-1, 47-2, and 47-3).

Table 47-1 shows the previously reported series of pediatric meningiomas as well as our own series of 21 pediatric meningiomas from a total of 928 tumors treated at Marmara University Medical Center and Acibadem University.

We analyzed various data by grouping some studies where data were more uniform. Unfortunately, it is difficult to consider all studies together due to variability of data considered by the authors.

EPIDEMIOLOGY

The incidence of meningiomas in pediatric populations in most series (see Table 47-1) ranges between 1% and 2% of all pediatric intracranial tumors in patients younger than 15 years of age as seen previously¹ in the studies listed in Table 47-1. Some studies found a slightly higher incidence. In an epidemiologic review of 1195 cases from a single institution, Rosemberg and Fujiwara reported the incidence of pediatric central nervous system (CNS) tumors.¹² They reported a 3% (32/1058) incidence of intracranial meningiomas. The relative frequency of grade I and II meningiomas was also reported by Rickert and Paulus¹³ in a combined series of 319 patients, which were 2.2% and 2.5% in newborn to 14- and newborn to 17-year-olds, respectively. The incidence of meningiomas relative to different pediatric age groups has been reported by several groups^4,14 (Table 47-4) and indicates the increasing incidence of meningioma with increased age in the pediatric group. These data indicate that pediatric meningiomas are not as rare as previously thought.

Lack of female predominance is well documented, and some studies found a slightly higher male representation in this group.^1,6,15,16 This was also noted in the series reviewed in this chapter as shown in Table 47-1, where there was slight male predominance of 1.13:1 ratio.^2,3,5–11 This is thought to be due to the lack of hormonal influence in the prepubertal age group, as hormonal effects beginning in this age would not manifest themselves for several years.¹⁷

The mean age at presentation is mostly reported at around 11 years of age and is generally later than in most other pediatric CNS tumors,^6,8,16 Another combined review of 84 patients younger than 19 years with menigiomas has found the peak age to be 12 years.¹⁷

Association with neurofibromatosis (NF) type 1 and 2 is also well established in the literature. In a review of four series with 126 patients, 1 in 4 children with meningioma were found to have NF2.¹⁷ The number of patients with neurofibromatosis in recent articles listed in Table 47-1 was only 16/159, or 11% of the total.

PREDISPOSING FACTORS

Radiation and neurofibromatosis are recognized as predisposing factors,^2,6,18 while the role of trauma has been controversial. Trauma as a risk factor for developing meningiomas was first suggested by Cushing and Eisenhart; however, it is not substantiated in more recent reports.¹⁹

The role of radiation in developing meningiomas is well established (Fig. 47-1). The initial major report indicating this connection was the study of children irradiated for tinea capitis in Israel.²⁰ In this study 10,834 children who had undergone low-dose (approximately 850 cGy) ionizing radiation were compared with 10,834 age- and sex-matched controls. The study found a fourfold increased risk of developing meningioma in the irradiated group,²⁰ which increased with increased dosage.

FIGURE 47-1 From patients treated at our institution showing pre- and postoperative MRI with contrast with multiple meningiomas and history of cranial radiation for residual hypothalamic glioma 11 years before presentation.

In a comprehensive study of radiation-induced brain tumors in childhood, Pettorini and colleagues²¹ reviewed the literature between 1960 and 2007. Review of the pediatric population from 60 articles resulted in 142 cases of which 33 were grade I and 7 were atypical meningiomas. The median age at radiation for grade I tumors was 5.4 years and that for atypical tumors was 5.1 years of age with a latency period of 13.7 years (range, 6 months–28 years) and 21.1 years (range 8–63 years) for grade I and II, respectively. Interestingly, the investigators did not find any correlation between the dose and the malignancy of the secondary tumor, although more than two thirds of both grade I and II meningiomas were exposed to high-dose radiotherapy.

Chromosomal abnormalities are also well associated with meningiomas, and the association between NF2 and meningioma is covered in Chapter 48. An abnormality of chromosome 22 has been reported for both sporadic and NF2-associated meningiomas. It is important to mention that meningioma was the first solid tumor to be associated with cytogenetic abnormalities, with most tumors showing monosomy of chromosome 22 and some with partial deletion or rearrangement of 22q.²² Between 40% and 60% of meningiomas showed allelic losses of this chromosome.²² Other chromosomal abnormalities in pediatric meningiomas involve chromosome 1p (in 5 of 13 cases) and chromosome 6q (4 of 13 cases) as reported by Bhattacharjee and colleagues.²²

In two large series Merten and colleagues²³ (48 patients) and Deen and colleagues²⁴ (51 patients) showed 23% and 24% of patients respectively were NF2 positive. Erdicler and colleagues¹⁵ reported 41% of 27 cases were associated with neurofibromatosis, of which 58% were NF1 and 42% were NF2.

Further, these children have a higher incidence of extracranial, intraocular, and multifocal meningiomas, indicating the need for close monitoring of these patients as well as investigating children with meningioma for the presence of neurofibromatosis. One should also keep in mind that NF2-related tumors are indolent⁵ and therefore conservative management may be an option depending on the clinical situation.

CLINICAL FEATURES

LOCATIONS

In terms of location, the distribution of pediatric meningiomas is similar to that of adult tumors. However, in contrast to adult meningiomas there appears to be a higher number of intraventricular (Fig. 47-2), sylvian (Fig. 47-3), and infratentorial tumors in children from reported series.

FIGURE 47-2 Pre- and postoperative MRI with contrast of patient with a large intraventricular meningioma. A, C, Coronal views. B, D, Sagittal views.

FIGURE 47-3 (A) Pre- and (B) postoperative MRI of a patient with sphenoid wing meningioma.

Lack of dural attachment is reported in many series.^1,9,26 Drake and colleagues¹ reported 23% of the tumors in their series which did not show dural attchment, and Merten and colleagues²³ and Doty and colleagues²⁷ 11% and 15%, respectively. These tumors were mostly sylvian fissure tumors while intraventricular tumors were excluded. Overall incidence of sylvian fissure meningiomas in the review by Drake and colleagues¹ of 207 cases was 3%.

Increased incidence of intraventricular location has also commonly been reported in pediatric menigiomas. In two larger series excluding spinal cases, Merten and colleagues²³ and Deen and colleagues²⁸ had 17% (8/47) and 4.8% (2/41) intraventricular tumors. However, Deen and colleagues,²⁴ calculating this proportion from the total number of their cases (51 patients) including 10 spinal cases, gave a lower percentage of 3.9% which they claim to be almost the same as in adult series. Among 159 patients included in Table 47-1 there were only 3 sylvian, but 20 (12.5%) intraventricular meningiomas were noted.