Spontaneous malignant transformation of trigeminal schwannoma: consideration of responsible gene alterations for tumorigenesis —a case report

AbstractMalignant peripheral nerve sheath tumors (MPNSTs) arising from the trigeminal nerves are extremely rare (only 45 cases, including the present case, have been published) and have been reported to develop de novo from the peripheral nerve sheath and are not transformed from a schwannoma or neurofibroma. Here, we report a case of MPNSTs of the trigeminal nerve caused by the malignant transformation of a trigeminal schwannoma, with a particular focus on genetic considerations. After undergoing a near-total resection of a histologically typical benign schwannoma, the patient presented with regrowth of the tumor 10  years after the primary excision. Histopathologic and immunochemical examinations confirmed the recurrent tumor to be an MPNST. Comprehensive genomic analyses (FoundationOne panel-based gene assay) showed that only the recurrent MPNST sample, not the initial diagnosis of schwannoma, harbored genet ic mutations, includingNF1-p.R2637* andTP53-p.Y234H, candidate gene mutations associated with malignant transformation. Moreover, the results of reverse transcription polymerase chain reaction showed that the fusion ofSH3PXD2A andHTRA1, which has been reported as one of the responsible genetic aberrations of schwannoma, was detected in the recurrent tumor. Taken together, we could illustrate the accumulation process of gene abnormalities for developing MPNSTs from normal cells via schwannomas.
Source: Brain Tumor Pathology - Category: Neurology Source Type: research