• Patients must have a body surface area (BSA) \>= 0.4 m\^2 at the time of study enrollment

• Patients must have a pilocytic astrocytoma or optic pathway glioma that has relapsed, progressed, or become refractory to conventional therapy; patients with neurofibromatosis (NF-1) are eligible

• Patients must have histologic verification of malignancy; histologic confirmation for patients with optic pathway gliomas will not be required

• Patients must have measurable residual disease, defined as tumor that is measurable in two perpendicular diameters on magnetic resonance imaging (MRI); for a lesion to be considered measurable, it must be at least twice the slice thickness on MRI (i.e. visible on more than one slice)

• To document the degree of residual tumor, the following must be obtained:

‣ All patients must have a brain MRI with and without contrast (gadolinium) within 1 week prior to study enrollment; for patients on steroids, baseline MRI scans must be performed after at least 1 week at a stable or decreasing dose of steroids

⁃ All patients with a history of spinal or leptomeningeal disease, and those patients with symptoms suspicious of spinal disease, must have a spine MRI with and without contrast (gadolinium) performed within 2 weeks prior to study enrollment

• Patients must have a Lansky or Karnofsky performance status score of \>= 60%; use Karnofsky for patients \> 16 years of age and Lansky for patients =\< 16 years of age

• Patients must have been treated with at least one prior treatment regimen that included carboplatin; patients who have received prior radiation therapy for this tumor are eligible

• Patients must have recovered (to Common Toxicity Criteria \[CTC\] version \[v.\]4.0 =\< grade 1 unless indicated below) from the acute toxic effects of all prior chemotherapy, immunotherapy, or radiotherapy prior to entering this study, with the exception of alopecia, weight changes and grade I or II lymphopenia

‣ Myelosuppressive chemotherapy: must not have received within 3 weeks of entry onto this study (6 weeks if prior nitrosourea or mitomycin-C)

⁃ Biologic (anti-neoplastic agent): at least 7 days after the last dose of a biologic agent; for agents that have known adverse events occurring beyond 7 days after administration, this period must be extended beyond the time during which adverse events are known to occur

⁃ Immunotherapy: at least 42 days after the completion of any type of immunotherapy, e.g. tumor vaccines

⁃ Monoclonal antibodies: at least 3 half-lives of the antibody after the last dose of a monoclonal antibody

⁃ Radiation therapy (RT): patients must have had their last fraction of craniospinal RT \>= 6 months prior to study entry and their last fraction of focal RT \>= 4 weeks prior to study entry; if the lesion used for on-study criteria is in the radiation field, there must be evidence of tumor progression after radiation therapy was completed

⁃ Study specific limitations on prior therapy:

• Patients who have received thalidomide are eligible if all acute thalidomide-related toxicity has resolved

∙ Patients must not have received lenalidomide previously

• Growth factor(s): must not have received within 2 weeks of entry onto this study

• Steroids: patients who are receiving corticosteroids must be on a stable or decreasing dose for at least 1 week prior to baseline MRI

• Peripheral absolute neutrophil count (ANC) \>= 1,000/uL

• Platelet count \>= 100,000/uL (transfusion independent)

• Hemoglobin \>= 8.0 g/dL (may receive red blood cell \[RBC\] transfusions)

• Creatinine clearance or radioisotope glomerular filtration rate (GFR) \>= 70 mL/min/m\^2 OR a serum creatinine based on age/gender as follows:

‣ 0.4 mg/dL (1 month to \< 6 months of age)

⁃ 0.5 mg/dL (6 months to \< 1 year of age)

⁃ 0.6 mg/dL (1 to \< 2 years of age)

⁃ 1.5 mg/dL (male) or 1.4 mg/dL (female) (13 to \< 16 years of age)

⁃ 1.7 mg/dL (male) or 1.4 mg/dL (female) (\>= 16 years of age)

• Total bilirubin =\< 1.5 x upper limit of normal (ULN) for age

• Serum glutamate pyruvate transaminase (SGPT) (alanine aminotransferase \[ALT\]) =\< 110 U/L; for the purpose of this study, the ULN for SGPT is 45 U/L

• Serum albumin \>= 2 g/dL

• No evidence of dyspnea at rest and a pulse oximetry \> 94% if there is clinical indication for determination

• Patients must be able to swallow intact capsules

• All patients and/or their parents or legal guardians must sign a written informed consent

• All institutional, Food and Drug Administration (FDA), and National Cancer Institute (NCI) requirements for human studies must be met