Spinal tap could replace brain surgery for young tumor patients

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: All patients must have a known or suspected diagnosis (based on pathology or imaging) of a primary brain tumor. All children and adolescent/young adult (AYA) patients =\< 21 years of age are eligible. AYA patients \< 40 are eligible with a primary brain tumor entity more common in children than adults. This includes: * medulloblastoma * non-medulloblastoma embryonal brain tumors * atypical teratoid rhabdoid tumors (ATRT) * ependymoma * CNS germ cell tumors * Diffuse midline glioma, H3K27M-altered * Diffuse hemispheric glioma, H3 G34-mutant * pineoblastoma * diffuse leptomeningeal glioneuronal tumor * diffuse brainstem glioma * pilocytic astrocytoma * choroid plexus carcinoma ELIGIBLE PATIENTS WILL BE STRATIFIED BY DIAGNOSIS AS FOLLOWS: * Stratum 1: Medulloblastoma * Stratum 2: High-grade glioma (IDH-wildtype) and DIPG o DIPG patients must meet clinical and imaging requirements for DIPG diagnosis. Patients with newly diagnosed diffuse intrinsic pontine gliomas (DIPGs), defined as tumors with a pontine epicenter and diffuse involvement of 2/5 or more of the pons, are eligible without histologic confirmation. Patients with brainstem tumors that do not meet these criteria or not considered to be typical intrinsic pontine gliomas will only be eligible for Stratum B if the tumors have been biopsied and are proven to be an anaplastic astrocytoma, glioblastoma multiforme, gliosarcoma, anaplastic mixed glioma or fibrillary astrocytoma. * Stratum 3: Low-grade glioma (IDH-wildtype) with multifocal/disseminated and/or leptomeningeal disease * Stratum 4: Diffuse Leptomeningeal Glioneuronal Tumor * Stratum 5: Pineoblastoma * Stratum 6: All other eligible tumor types * DISEASE STATUS: Participants will be eligible at any stage of disease. * AGE: All children and adolescent/young adult (AYA) patients =\< 21 years of age are eligible. AYA patients \< 40 are eligible with a primary brain tumor entity more common in children than adults * CEREBROSPINAL FLUID (CSF) COLLECTION: Patients must have a clinical indication for at least one CSF (lumbar, cisternal or ventricular) collection, or clinical circumstance where CSF sampling is feasible with no or minimal risk (e.g., endoscopic third ventriculostomy, external ventricular drain). * INFORMED CONSENT: The patient or parent/guardian can understand the consent and is willing to sign a written informed consent document according to institutional guidelines. Exclusion Criteria: * DIAGNOSIS: Given the extremely low rate of CSF cfDNA positivity in patients with localized, non-disseminated low-grade glioma, those patients will be excluded from participation.