Bilateral ganglioglioma of the trigeminal nerve in an 83-year-old man.

Gangliogliomas are well-differentiated, mixed glio-neuronal tumors of the CNS that are most frequently localized within the temporal lobe. In a minority of cases, gangliogliomas have been described in the brain stem where they may critically impinge anatomical structures. Rarely, ganglioglioma develop in cranial nerves, almost exclusively in the optic pathway, where they usually present as singular space-occupying masses. Here, we report on an 83-year-old patient who presented with unusual symmetrical, bilateral gangliogliomas of the trigeminal nerves. These tumors showed an exophytic growth within the subarachnoid space toward the Gasserian ganglion and surprisingly appeared as isointense masses on T1- and T2-weighted MRI. Due to their bilateral appearance, we performed array-comparative genomic hybridization (aCGH) on the gangliogliomas to address the possibility of an underlying tumor syndrome in this patient. To our knowledge, this is the first case of bilateral ganglioglioma of the trigeminal nerve described so far.

Ablation of T cell immunity differentially influences tumor risk in inbred BD rat strains.

Inbred rat strains BDIX and BDIV are constitutionally susceptible and resistant, respectively, to the development of malignant peripheral nerve sheath tumors (MPNST) induced by neonatal exposure to N-ethyl-N-nitrosourea (EtNU). They represent a model system for analysis of molecular and cellular processes underlying differential cancer susceptibility. A point mutation in the Neu/ErbB-2 gene is an early marker of Schwann precursor cells at high risk of malignant conversion and is diagnostic of the resulting MPNST predominantly developing in the trigeminal nerves. Initially considerable amounts of Neu/ErbB-2-mutant cells arise in nerve tissue of both rat strains subsequently disappearing in resistant BDIV rats, but persisting and giving rise to MPNST in susceptible BDIX animals. An almost identical cellular immune response-sequentially involving macrophages, T helper- and cytotoxic T lymphocytes-is mounted in the trigeminal nerves of EtNU-treated rats of both strains. In this study, T cell maturation was prevented by neonatal thymectomy following EtNU-exposure. While resistance against MPNST development significantly decreased in BDIV rats MPNST incidence and survival time remained unaltered in thymectomized BDIX rats. Contrary to euthymic animals a number of both thymectomized BDIV and BDIX rats developed MPNST lacking the Neu/ErbB-2-mutation. This suggests that Schwann cells initiated by other genetic alterations can progress to full malignancy in immune-compromised rats only. T cell-dependent resistance against tumorigenesis originating from non-Neu/ErbB-2-mutant Schwann precursors might thus be shared by both strains while BDIV T lymphocytes additionally prevent the development of Neu/ErbB-2-mutant MPNST. Rat strain-specific differences in the interaction of T lymphocytes with (pre)malignant Neu-mutant cells may thus critically contribute to susceptibility and resistance towards EtNU-induced MPNST development.

A non-NF2 case of schwannomas of vestibular and trigeminal nerves with different genetic alterations of NF2 gene: case report.

BACKGROUND: We report a patient with 2 separate schwannomas, a vestibular schwannoma and a trigeminal schwannoma, that were attached to each other and appeared to be a single tumor on imaging studies. CASE DESCRIPTION: The patient, without any family history of neurofibromatosis, presented with a progressive hearing loss and mild left facial nerve palsy. Magnetic resonance imaging showed a snowman-like tumor in the left cerebellopontine angle. Surgical exposure revealed that the tumor consisted of 2 "kissing" schwannomas, a trigeminal and vestibular schwannoma. Molecular genetic analysis detected a 1-base pair deletion at exon 10 of the neurofibromatosis type 2 (NF2) gene in the trigeminal schwannoma, but not in the acoustic schwannoma. However, loss of heterozygosity at chromosome 22q (D22S282 and D22S929) was detected in both tumors, losing the same allele. CONCLUSION: Multiple schwannomas in non-NF2 patients are extremely rare, and possible causes include simple coincidence or germline genetic alteration of adjacent gene on chromosome 22q, similar to the cause recently suggested in familial schwannomatosis. Although not always possible, molecular genetic examination may help to understand the underlying mechanism and would be warranted in such cases.