Evaluation of NF2 Gene Deletion in Pediatric Meningiomas Using Chromogenic In Situ Hybridization

A Treatise on Pediatric Meningiomas: Single-center Retrospective Cohort Experience and Review of Literature

Background

Pediatric meningiomas are infrequently encountered in clinical practice. In comparison to adults, they have a distinct pathophysiology and clinical presentation. They are benign but locally aggressive tumors. Radical excision often culminates in good outcome.

Aim

The aim of this study was to study the demographic profile, clinico-radiological features, pathophysiology, and surgical outcome of childhood meningiomas.

Materials and Methods

The case records of patients <18 years of age operated for meningiomas in our institute from 1985 to 2015 were retrieved. The demographic profile, clinical and radiological features, surgical approach, extension of resection, and surgical outcome were recorded and subsequently analyzed.

Results

Among 37 patients, 20 were males and 17 were females. The mean age was 13 years. Predisposing etiologies such as neurofibromatosis and radiation exposure were identified in 20% of the study population. There were 31 intracranial and 6 spinal meningiomas. Headache associated with vomiting was the most common presenting complaint. Majority were supratentorial tumors. A safe maximal excision was attempted in each case. Recurrence was noted in five patients. Average follow-up was approximately 24 months. Two patients succumbed to the illness. Approximately, 30% of patients were rendered morbid.

Conclusion

Although rare, pediatric meningiomas are biologically different from their adult counterparts. They have a male predominance, common in intraventricular region and cystic in nature. Radical excision is associated with good prognosis. Although benign, they are aggressive in nature and have a tendency to recur. The response to adjuvant therapy is modest. Further molecular research and genetic studies are necessary to understand the biology of pediatric meningiomas, which will help in the identification of targeted molecular therapy.

Clinicopathological and molecular characteristics of pediatric meningiomas

Molecular and clinical characteristics of pediatric meningiomas are poorly defined. Therefore, we analyzed clinical, morphological and molecular profiles of pediatric meningiomas. Forty pediatric meningiomas from January 2002 to June 2015 were studied. 1p36, 14q32 and 22q-deletion were assessed by fluorescent in situ hybridization and mutations of most relevant exons of AKT, SMO, KLF4, TRAF and pTERT using sequencing. Expression of GAB1, stathmin, progesterone receptor (PR), p53 along with MIB-1 LI was examined using immunohistochemistry. There were 36 sporadic and four NF2 associated meningiomas. Among sporadic meningiomas, the majority (72.2%) of cases harbored 22q-deletion. Difference in frequency of combined 1p/14q deletion in Grade-I versus Grade-II/III tumors was not significant (13.7% vs 28.5%, P = 0.57). PR immunoreactivity was seen in 65.5% of Grade-I and 14.2% of Grade-II/III tumors (P = 0.03). The majority (97.2%) of meningiomas were immunonegative for p53. Stathmin and GAB co-expression was observed in 58.3% of cases. Notably, AKT, SMO, KLF4, TRAF7 (exon 17) and pTERT mutations were seen in none of the cases analyzed. 1p/14q codeletion was frequent in skull base as compared to non-skull base meningiomas (23% vs 11.1%, P = 0.37). All NF2 meningiomas harbored 22q-deletion and showed GAB and stathmin co-expression while none showed 1p/14q loss. Pediatric meningiomas share certain phenotypic and cytogenetic characteristics with adult counterparts, but GAB and stathmin co-expression in the majority of cases and non-significant difference in frequency of 1p/14q co-deletion between low- and high-grade meningiomas indicate an inherently aggressive nature. Characteristic AKT/SMO, KLF4/TRAF7 and pTERT genetic alterations seen in adults are distinctly absent in pediatric meningiomas.

Intracranial meningiomas and neurofibromatosis type 2

PURPOSE

In spite of the few clinical studies regarding the occurrence of intracranial meningiomas, their prognosis in neurofibromatosis type 2 (NF2) has not been accurately assessed and their management remains controversial. This study aims to compare NF2 patients with intracranial meningiomas to those without, and consequently to identify prognostic factors in attempt to improve the management of these tumors.

METHODS

This retrospective study includes a total of 80 NF2 patients followed at Lille Hospital Center between 1987 and 2011. The diagnosis of NF2 was confirmed either because the patient met the Manchester criteria or by the presence of genetic mutation. Clinical, radiological and genetic data were retrospectively recorded and analyzed. Patients underwent annual cranial and spinal MRI. Both location and size of each tumor were reported.

RESULTS

The mean follow-up period was 8.8 years (range 1-24 years; SD: ±0.8) and the mean age at diagnosis was 27.2 years (range 6-73 years; SD: ±1.7). Among all patients, 34 harbored intracranial meningiomas. Patients with intracranial meningiomas had a higher number of intracranial schwannomas, spinal tumors and cutaneous tumors (p < 0.05). They underwent more surgical procedures (p < 0.012). Twenty five intracranial meningiomas were surgically removed in 17 patients. The decision to perform surgery was taken in 10 cases for symptomatic tumors and in 15 cases for growing asymptomatic tumors determined by radiology. The histological analysis found a high rate of fibroblastic, transitional or grade 2 meningiomas preferentially located at the cerebri falx.

CONCLUSION

Intracranial meningiomas are common in NF2. They are associated with poor prognosis factors. Clinical and radiological monitoring could lead to early treatment of these tumors both when clinical symptoms are present and in case of proven radiological evolution, and thus trying to maintain a favorable functional prognosis for as long as possible.

Childhood and juvenile meningiomas

PURPOSE

The purpose of this paper was to study the clinical characteristic, treatment, and prognosis of childhood meningioma.

MATERIALS AND METHODS

Fifty-four meningioma cases below the age of 18 have been treated in Huashan Hospital in the last 15 years (from 1993 to 2008), their sex and age distribution, clinical manifestation, radiological finding, pathological subtype, treatment, and prognosis are retrospectively analyzed, and the results are compared with those reported in the literature.

RESULTS

The ratio of male to female was 1.16:1 (29:25) and mean age was 13.14 years (ranging from 2.75 to 18 years). Five patients in this series were associated with neurofibromatosis-2. The most common symptoms and signs were the signs of increased intracranial pressure including headache, papilledema, and vomiting. The most common radiological finding was homogeneous enhancement with contrast. The most common locations of meningiomas in this series were intraventricular and anterior/middle fossa. All of these patients were surgically treated; resection both in Simpson grades I and II could be achieved in 39 out of 54 patients. Perioperative mortality was 3.7% (2 out of 54); the most common postoperative complications were intracranial infection and injury of cranial nerve. Fibroblastic meningiomas were the most common pathological subtype, and malignant and atypical meningiomas (both of grades II and III according to WHO classification) accounted for 18.5% of the whole series.

CONCLUSION

Childhood meningiomas are scarce in clinical practice, which are characterized with its male predominance, large size, distinctive radiological features, and high rate of atypical/malignant histological subtypes; favorable outcome is accessible with total removal.

Radiation-induced meningiomas: clinical, cytogenetic, and microarray features

Limited information exists about the clinical and biological features of radiation-induced meningiomas (RIMs), particularly those that follow high-dose therapeutic radiation. We report our experience with 20 patients with RIMs (16 following high-dose radiotherapy) treated at our institution from 1993-2006. Patients (14 female, 6 male) had intervals from first radiotherapy to RIM diagnosis of 11-63 years; 12 had at least one RIM occur at an interval of 30 years or more after initial radiotherapy. Multiple RIMs were seen in six patients, with one patient developing his six RIMs sequentially over a 22-year interval. Most RIMs could be managed surgically, either with a single extensive resection or additional resection(s). Adjuvant stereotactic radiosurgery, external beam radiation, or chemotherapy were required in a minority (n = 6). Most were WHO grade I meningiomas. Complex karyotypes were found in three of four cases and abnormalities of chromosome 1p and/or LOH 1p36 were identified in five of 11 informative cases. Gene-expression microarray analysis of RIMs (n = 5) compared to non-RIMs (MEN, n = 6) and a panel of other tumors (n = 62) showed that RIM gene-expression was similar to that seen in MEN, and by clustering analysis did not separate from them. However, microarray comparative gene-expression analysis did demonstrate a few genes with significant differences in the expression level in RIM versus MEN. Of note, NF2 was under-expressed in four of five RIMs (P = 0.0065), at a similar level as measured in MEN.