10–20% of CNS tumors in children: 150–300 cases of pediatric brainstem tumors arise in the United States each year, representing 10–20% of all CNS tumors in children (6, 9, 10). 75% of all brainstem tumors are diffuse gliomas (6).
Diffuse intrinsic pontine gliomas = 75%: Approximately 75% of brainstem gliomas are diffuse intrinsic pontine gliomas. Consequently, 120–240 diffuse intrinsic pontine gliomas are diagnosed in the United States each year.
Dorsally exophytic gliomas = 10–20%: Dorsally exophytic tumors represent 10–20% of brainstem tumors. Between 15 and 60 such tumors are diagnosed in the United States each year.
Cervicomedullary gliomas = 5–10%: Cervicomedullary gliomas represent 5–10% of brainstem tumors. Between 7 and 30 new cervicomedullary tumors are diagnosed in the United States each year.
Midbrain tumors: These lesions are rare and most studies in the literature are case reports.
6.5 years median age at presentation: Brainstem tumors in all subgroups are primarily seen in children ages 6–9 years (median age 6.5 years), although they have been diagnosed in patients of all ages (6, 9-12).
None: There appears to be an equal distribution between males and females for all brainstem tumor subgroups (6, 9, 11, 12).
Not known: Sufficient data are not available to determine if there is a geographic propensity to brainstem gliomas.
None known: No specific risk factors have been described relating environmental or infectious agents to the incidence of brainstem gliomas.
Relationships to Other Disease States and Syndromes
Neurofibromatosis: Pollack et al. have described an apparent association in patients between NF1 and the incidence of brainstem gliomas. These tumors, whether diffuse or focal, appear to have a more benign course compared with tumors from patients without NF1 (6, 14-15).