Pediatric rhabdoid meningioma: a morphological, immunohistochemical, ultrastructural and molecular case study.

Rhabdoid meningioma is an uncommon meningioma variant categorized as WHO grade III. The majority of cases occur in adulthood. Herein, we describe a right fronto-temporal rhabdoid meningioma affecting a 3-year-old boy. The lesion measured approximately 4 cm in diameter and incorporated the ipsilateral middle cerebral artery. Sub-total surgical excision of the mass was performed. Histologically, the tumor was mainly composed of globoid plump cells with inclusion-like eosinophilic cytoplasm, peripheral nuclei, prominent nucleoli and occasional intra-nuclear cytoplasmic pseudo-inclusion. The cells appeared in many areas loosely arranged and focally disclosed a papillary architecture. At immunohistochemistry, the tumor cells were EMA, vimentin, HHF35, PgR, INI-1 and p53 positive. The proliferative index (Mib-1) was 15% in the most positive areas. Ultrastructurally, tumoral cells showed an abundant cytoplasm, which was filled with numerous intermediate filaments. Desmosomal junctions were seen. RT-PCR revealed the presence of NF2 gene expression. Molecular study did not indicate alterations of the INI-1 gene, whereas it showed the presence of Pro72Arg in exon 4 at heterozygous state in the TP53 gene. Morphologic features along with immunohistochemical, ultrastructural and molecular results were consistent with the diagnosis of rhabdoid meningioma. The patient was treated with chemotherapy. The lesion remained stable after 33 months of follow-up. Rhabdoid meningiomas rarely occur in children. Owing to its rarity, each new case should be recorded to produce a better clinical, pathological, molecular, prognostic and therapeutic characterization of this lesion.

Embryonal tumor with abundant neuropil and true rosettes: morphological, immunohistochemical, ultrastructural and molecular study of a case showing features of medulloepithelioma and areas of mesenchymal and epithelial differentiation.

Embryonal tumors are a group of malignant neoplasms that most commonly affect the pediatric population. Embryonal tumor with abundant neuropil and true rosettes is a recently recognized rare tumor. It is composed of neurocytes and undifferentiated neuroepithelial cells arranged in clusters, cords and several types of rosettes in a prominent neuropil-rich background. We describe a new case of this tumor. The patient, a 24-month-old female infant, was referred to the Meyer Children's Hospital with a history of right brachio-crural deficit associated with occasional episodes of headache and vomiting. Computed tomography scan and MRI revealed a large bihemispheric mass. The patient underwent two consecutive surgeries. The resultant surgical resection of the tumor was macroscopically complete. The postoperative period was uneventful. On light microscopy the tumor showed a composite morphology: embryonal tumor with abundant neuropil and true rosettes (specimen from the first surgery); medulloepithelioma with mesenchymal and epithelial areas (specimen from the second surgery). The immunohistochemistry evidenced the heterogeneous (neuronal, mesenchymal and epithelial) immunoprofile of tumoral cells. By real-time polymerase chain reaction (RT-PCR), the PTEN gene expression in the tumor was lower than in the five non-neoplastic brain tissues used as control. Mutation analysis did not show any variation in INI-1 and PTEN sequence while P53 analysis showed the presence of homozygote P72R variation. Fluorescent in situ hybridization analysis showed polysomy of chromosome 2 while amplification of N-MYC was not detected. Owing to the rarity of embryonal tumor with abundant neuropil and true rosettes, each new case should be recorded to produce a better clinical, pathological and molecular characterization of this lesion.

Hox-D genes expression in pediatric low-grade gliomas: real-time-PCR study.

HOX genes encode transcription factors, which play a key role in morphogenesis and cell differentiation during embryogenesis. Several observations indicate that a deregulated expression of these genes may result in tumor development and progression. Actually, several HOX genes are aberrantly expressed in many tumors and cell lines derived from them. Little is known about the expression of HOX genes in brain tumors. In the present work, we study the relative expression of HOX-D genes (D1, D3, D4, D8, D9, D10, D11, D12, D13) with real-time polymerase chain reaction in a group of 14 pediatric low-grade gliomas. We compare the HOX-D expression level of the 14 tumors with the average expression level of six non-neoplastic human brain tissues. HOX-D1 and HOX-D12 resulted over-expressed in neoplastic samples with respect to non-neoplastic brain parenchyma. Conversely, HOX-D3 was expressed at a lower level in gliomas with respect to non-neoplastic brain. HOX-D4, HOX-D11, and HOX-D13 were never expressed. HOX-D8, HOX-D9, and HOX-D10 were exceptionally expressed in non-neoplastic samples and irregularly expressed in tumors. The observation that all but three HOX-D genes studied are expressed with different pattern in neoplastic and non-neoplastic brain tissue may support the hypothesis that HOX-D genes play a role in the pathogenesis of pediatric low-grade gliomas.

Pediatric brain tumors: mutations of two dioxygenases (hABH2 and hABH3) that directly repair alkylation damage.

Alkylating agents, commonly used for brain tumor therapy, induce DNA and RNA lesions that, if not repaired, drive cells to apoptosis. Thus, cellular mechanisms that are responsible for nucleic acid repair are possibly involved in drug resistance. This work analyzes hABH2 and hABH3, two human Fe(II)-dependent dioxygenases in pediatric brain tumors that are treated with alkylating agents. We analyzed 25 brain tumor samples for hABH2 and hABH3 mutations; a subset of samples was tested for quantitative expression with Real-Time PCR. Sequencing analysis showed two new mutations in two glioma patients, one of hABH2 coding sequence (I141 V) and the other of hABH3 (D189 N). The mutation at codon 189 falls in a crucial region of the protein. All subjects analyzed by Real-Time PCR showed an enhanced expression of the two genes, particularly of hABH2. This is the first study of hABH2 and hABH3 in pediatric brain tumors; further molecular investigations of their mutations and expression may help determine their role in response to chemotherapy.

Monotherapy with thalidomide for treatment of spinal cord hemangioblastomas in a patient with von Hippel-Lindau disease.

Von Hippel-Lindau (VHL) disease is a cancer-prone syndrome characterized by abnormalities in vascular proliferation and the development of both the visceral and CNS tumors. Complications from hemangioblastoma are among the principal causes of death from this syndrome. Antiangiogenic therapy has been used with different modalities in patients suffering from such complications. Here, we describe an adolescent with VHL complicated by progressive, multifocal spinal hemangioblastomas. Treatment with single-agent thalidomide over the course of 3 years was associated with an unexpected stabilization of the disease. The antiangiogenic effect of thalidomide may be associated with the control of progressive hemangioblastoma.

Intracavitary chemotherapy (Gliadel) and oral low-dose etoposide for recurrent anaplastic ependymoma.

Anaplastic ependymoma is associated with a higher incidence of tumor recurrence and its prognosis still remains unsatisfactory. Consolidated therapy for ependymoma includes surgery followed by focal radiotherapy when resection is incomplete. In the case of relapse treatment, options are limited especially for patients who have already received radiotherapy. We sought to establish the feasibility of administering low-dose oral etoposide (50 mg/m(2)/day for 21 days) in combination with the implantation of intracavitary carmustine (BCNU) wafers (Gliadel) at the gross total resection for achieving synergistic treatment in three children affected by recurrent anaplastic ependymoma. All patients had Karnofsky performance scale (KPS) scores >80%. The therapy was tolerated safely and well in all patients without any post-surgery complications. After BCNU wafer implantation, all patients achieved radiological and clinical stabilization for an average period of 3 months. Two patients relapsed after 4 months as shown in brain MRIs. The other patient went to progression two months after the Gliadel implantation. This multimodal approach was not effective for the treatment of refractory anaplastic ependymoma and further studies are required in order to define the role of the combination of multidrug systemic chemotherapy with BCNU wafer implantation in children with high-risk brain tumors.

Glioneuronal tumor with neuropil-like islands: clinical, morphologic, immunohistochemical, and molecular features of three pediatric cases.

Glioneuronal tumors with neuropil-like islands are rare. The 1st reported cases were localized in the cerebral hemispheres of adults, showed homogeneous histopathologic features (infiltrating astrocytic growth and neuropil-like islands rimmed by neuronal cells), and had an unfavorable behavior. We report 3 pediatric cases (1 boy and 2 girls, ages 4, 6, and 8 years, respectively). The boy had a cerebral tumor, and the girls had a spinal tumor. The younger girl also had multiple posterior fossa lesions. The boy and older girl underwent a gross total resection. The younger girl underwent a subtotal resection of the spinal tumor; posterior fossa lesions were not surgically treated. The boy and younger girl are in complete remission at 33 and 24 months, respectively, after surgery and subsequent high-dose chemoradiotherapy. The older girl had a recurrence that was partially resected. Afterward, she started high-dose chemoradiotherapy and had an optimal radiologic response at 4 months follow up. Microscopically, the common denominator was the presence of synaptophysin-positive neuropil-like islands. One tumor showed ependymal features (pseudorosettes and punctate epithelial membrane antigen immunopositivity). Two tumors had 1p deletion. 19q deletion, MGMT gene promoter methylation, EGFR amplifications or polysomy, and EGFR, IDH1, IDH2, and TP53 genes mutation analyses yielded negative results. In conclusion, glioneuronal tumor with neuropil-like islands can affect children, arise in the spinal cord, and show ependymal features in its glial component. A high-dose chemoradiotherapy program is effective.

Type A microsatellite instability in pediatric gliomas as an indicator of Turcot syndrome.

Microsatellite instability (MSI) is present in hereditary conditions due to mismatch repair (MMR) gene mutations. Following MSI analysis, tumor samples are classified into MSS (stable), MSI-L (low instability), and MSI-H (high instability) based on the fraction of unstable loci. Another MSI-based classification takes into account the size difference between mutant alleles in tumor DNA compared to wild-type alleles; two types of MSI, A and B, are recognized using this approach, type A being characterized by smaller, more subtle allelic shifts compared to type B. Biallelic mutations of MMR genes are associated with pediatric cancers, including glial tumors, in Turcot syndrome type 1 (TS1). However, most TS1-associated gliomas so far analyzed did not display MSI. We investigated the frequency of MSI in a series of 34 pediatric gliomas of different grade using a panel of five mononucleotide quasimonomorphic markers. Subtle qualitative changes were observed for the majority of markers in two glioblastomas (5.9% of the total series and 33.3% of glioblastomas). In both cases, family histories were compatible with TS1, and mutations of the PMS2 and MLH1 genes were identified. In one family, the MSI patterns were compared between the glioblastoma and a colon cancer from an affected relative, showing a clear qualitative difference, with the former displaying type A and the latter type B instability, respectively. These results were confirmed using additional microsatellite markers, indicating that knowledge of the association between TS1-related glial tumors and subtle type A MSI is important for full ascertainment of TS1 patients and appropriate counselling.

Maximizing results in craniofacial surgery with bioresorbable fixation devices.

The resorbable plating system allows the infant's skull to grow once the system is resorbed, thus not inhibiting the necessary developmental growth seen with the titanium system. Despite marked improvements in long-term outcomes, there are still technical points that can be followed to maximize outcome while reducing and possibly eliminating minor complications such as plate palpability and visibility through the skin as well as skin breakdown over the plate. A retrospective electronic chart review was performed on the pediatric patient population who underwent craniofacial surgery with the use of resorbable fixation devices by the senior author (LG). Fifty-two patients underwent surgical correction for craniosynostosis with resorbable material (Craniosorb, Lactosorb, or Biosorb PDX). This series included patients with brachycephaly (17), anterior plagiocephaly (unilateral coronal synostosis; 16), trigonocephaly (11), multisuture craniosynostosis (7), and Cohen's craniotelencephalic dysplasia (1). The mean age at the time of the operation was 8 months and the mean follow up was 17 months. Eight patients experienced complications related to the resorbable material. Seven of the eight had complete resolution of symptoms after conservative treatment and one patient had complete resolution of the skin infection after plate removal. The purpose of this study was to evaluate the risks and complications with the use of resorbable material to establish guidelines for avoidance of surgical pitfalls that lead to increased risk of morbidity with the use of this material, particularly as it relates to plate visibility under the skin, plate palpability, skin breakdown, and skin infections over the plating system.