An Incidental Diffuse Midline Glioma Found at Autopsy

Abstract

This case shows an unexpected midline glioma found at autopsy. Two siblings were riding on a single bicycle on the side of a road. The 13-year-old brother was seated and steering the bicycle, while the 14-year-old sister held onto the back. The bicycle veered left into traffic and was struck by a vehicle. The siblings were admitted to the local Level 1 trauma center, but both later succumbed to injuries. Autopsies were performed on the children, including brains for neuropathologic evaluation. The brother was found to have an infiltrating astrocytoma located in the left middle cerebellar peduncle, with extension to the pons and medulla. His hospital course included several imaging studies using CT and MRI modalities. However, this lesion was not identified until the postmortem neuropathologic examination. This rare case shows the continued need for postmortem autopsy and the current limitations of medical imaging.KEYWORDS: forensic science, forensic pathology, neuropathology, diffuse midline (pontine) glioma, accidental death, unexpected neurological finding This case represents unexpected findings during a neuropathologic evaluation of a traumatic brain injury victim. The 13-yearold victim was known to have edema in the cerebellar peduncles on premortem MRI; however, the scans were limited due to significant artifact arising from the hardware of a cervical spine fusion. Examination at the time of autopsy revealed a diffuse expansion of the left middle cerebellar peduncle. Histological examination proved this expansion to be due to a midline infiltrating astrocytoma, or "midline glioma." Two siblings were transferred by ambulance to a Level 1 trauma center in extremis after a bicycle versus motor vehicle collision. Witnesses described two unhelmeted siblings on a single bicycle with the 13-year-old brother seated and steering. His 14-year-old sister clung to him and rode on the back of the bicycle. The bicycle reportedly veered left into traffic and was struck by a motor vehicle. The 13-year-old male was intubated at the scene and had a GCS (Glasgow Coma Scale) of 3. EMS also reported the boy to be in pulseless electrical activity (PEA) upon their arrival, with approximately 5 min of CPR returning him to spontaneous circulation. On admission to the ICU, he had an atlanto-occipital dislocation (without severance of the cord), subdural hematoma, suspected diffuse axonal injury, splenic laceration, lung contusion, sacral fractures, and a neck hematoma. Neurological surgery consultation resulted in placement of an extraventricular device to monitor intracranial pressure. Eventually, an occiput to C3 posterior fusion with metallic instrumentation was performed to stabilize his upper cervical spine. On hospital day 6, an MRI of the brain was obtained for prognosis. This MRI showed a subdural hematoma in the right retroclival region with compression of the pons, medulla, and cervical cord. Diffuse swelling was noted in the cerebellar peduncles, and evaluation of the posterior fossa was limited due to artifact...

Oncohistones: a roadmap to stalled development

“…Interestingly, the age of diagnosis of paediatric H3K27M gliomas coincides with a period of pontine expansion during normal development linked primarily to increased myelination from proliferating and differentiating OPCs [79]. This normal proliferative activity may be key to acquiring additional oncogenic partner mutations since rare incidental reports of H3K27M‐mutant diffuse midline gliomas in asymptomatic individuals [80], or in initial low‐grade gliomas that transform on recurrence [81], suggest that there may be a significant latency between acquisition of the early clonal H3K27M mutation [82] and the rapid tumour growth associated with high‐grade gliomas.…”