Cellular Classification

Brain stem gliomas are classified according to their location, radiographic appearance, and histology (when obtained). Brain stem gliomas may occur in the pons, midbrain, tectum, dorsum of the medulla at the cervicomedullary junction, or in multiple regions of the brain stem. The tumor may contiguously involve the cerebellar peduncles, cerebellum, the cervical spinal cord, and/or thalamus. The majority of childhood brain stem gliomas are diffuse, fibrillary astrocytomas that involve the pons (diffuse intrinsic pontine gliomas [DIPG]), often with contiguous involvement of other brain stem sites.[1,2] The prognosis is extremely poor for these tumors. The biology of diffuse pontine glioma is limited by the lack of pathological tissue available for study, but this is slowly being remedied by occasional upfront biopsies or analysis of immediate postmortem autopsy specimens. Overexpression of epidermal growth factor receptor, platelet-derived growth factor receptor alpha, and poly (ADP-ribose) polymerase (PARP-1) have been identified.[3,4] Focal pilocytic astrocytomas have a more favorable prognosis. These most frequently arise in the tectum of the midbrain, focally, within the pons, or at the cervicomedullary junction where they are often exophytic, and have a far better prognosis than diffuse intrinsic tumors.[5-7]

Primary tumors of the brain stem are most often diagnosed based on clinical findings and on neuroimaging studies using magnetic resonance imaging.[8,9] Histologic confirmation of presumed DIPG is usually unnecessary. Biopsy or resection may be indicated for brain stem tumors that are not diffuse and intrinsic or when there is diagnostic uncertainty based on imaging findings. New approaches with stereotactic needle biopsy may make biopsy safer.[10]

References

1. Freeman CR, Farmer JP: Pediatric brain stem gliomas: a review. Int J Radiat Oncol Biol Phys 40 (2): 265-71, 1998.  [PUBMED Abstract]
   
   
2. Laigle-Donadey F, Doz F, Delattre JY: Brainstem gliomas in children and adults. Curr Opin Oncol 20 (6): 662-7, 2008.  [PUBMED Abstract]
   
   
3. Gilbertson RJ, Hill DA, Hernan R, et al.: ERBB1 is amplified and overexpressed in high-grade diffusely infiltrative pediatric brain stem glioma. Clin Cancer Res 9 (10 Pt 1): 3620-4, 2003.  [PUBMED Abstract]
   
   
4. Zarghooni M, Bartels U, Lee E, et al.: Whole-genome profiling of pediatric diffuse intrinsic pontine gliomas highlights platelet-derived growth factor receptor alpha and poly (ADP-ribose) polymerase as potential therapeutic targets. J Clin Oncol 28 (8): 1337-44, 2010.  [PUBMED Abstract]
   
   
5. Epstein F, McCleary EL: Intrinsic brain-stem tumors of childhood: surgical indications. J Neurosurg 64 (1): 11-5, 1986.  [PUBMED Abstract]
   
   
6. Edwards MS, Wara WM, Ciricillo SF, et al.: Focal brain-stem astrocytomas causing symptoms of involvement of the facial nerve nucleus: long-term survival in six pediatric cases. J Neurosurg 80 (1): 20-5, 1994.  [PUBMED Abstract]
   
   
7. Pollack IF, Pang D, Albright AL: The long-term outcome in children with late-onset aqueductal stenosis resulting from benign intrinsic tectal tumors. J Neurosurg 80 (4): 681-8, 1994.  [PUBMED Abstract]
   
   
8. Albright AL, Packer RJ, Zimmerman R, et al.: Magnetic resonance scans should replace biopsies for the diagnosis of diffuse brain stem gliomas: a report from the Children's Cancer Group. Neurosurgery 33 (6): 1026-9; discussion 1029-30, 1993.  [PUBMED Abstract]
   
   
9. Liu AK, Brandon J, Foreman NK, et al.: Conventional MRI at presentation does not predict clinical response to radiation therapy in children with diffuse pontine glioma. Pediatr Radiol 39 (12): 1317-20, 2009.  [PUBMED Abstract]
   
   
10. Cartmill M, Punt J: Diffuse brain stem glioma. A review of stereotactic biopsies. Childs Nerv Syst 15 (5): 235-7; discussion 238, 1999.  [PUBMED Abstract]