Inclusion Criteria:

          -  Participants must be able to understand and be willing to sign a written informed
             consent document.

          -  Men and woman who are at least 18 years of age on the day of consenting to the study.

          -  Histologically documented PCNSL or histologically documented systemic diffuse large
             B-cell lymphoma (DLBCL).

          -  Patients must have relapsed/refractory PCNSL or relapsed/refractory SCNSL

          -  All patients need to have received at least one prior CNS directed therapy. There is
             no restriction on the number of recurrences.

          -  Patients with parenchymal lesions must have unequivocal evidence of disease
             progression on imaging (MRI of the brain or head CT) 21 days prior to study
             registration. For patients with leptomeningeal disease only, CSF cytology must
             document lymphoma cells and/or imaging findings consistent with CSF disease 21 days
             prior to study registration (at the discretion of the investigator).

          -  Participants must have an ECOG performance status of 0, 1, or 2.

          -  Participants must have adequate bone marrow and organ function shown by:

               -  Absolute neutrophil count (ANC) ≥ 1.0 x 10^9/L

               -  Platelets ≥ 75 x 10^9/L and no platelet transfusion within the past 21 days prior
                  to study registration

               -  Hemoglobin (Hgb) ≥ 8 g/dL and no red blood cell (RBC) transfusion within the past
                  21 days prior to study registration

               -  International Normalized Ratio (INR) ≤ 1.5 and PTT (aPTT) ≤ 1.5 times the upper
                  limit of normal

               -  Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3 times the
                  upper limit of normal

               -  Serum bilirubin ≤ 1.5 times the upper limit of normal; or total bilirubin ≤ 3
                  times the upper limit of normal with direct bilirubin within the normal range in
                  patients with well documented Gilbert Syndrome.

               -  Serum creatinine ≤ 2 times the upper limit of normal

               -  Escalation: calculated creatinine clearance(CrCl) ≥ 60ml/min using the
                  Cockcroft-Gault equation (Men: CrCl (min/ml) = (140-age) X (actual weight in kg)
                  / 72 X serum creatinine (mg/dL); Women: CrCl (ml/min) = (140-age) X (actual
                  weight in kg) X 0.85 / 72 X serum creatinine (mg/dL))

               -  Extension: calculated creatinine clearance(CrCl) ≥30ml/min using the
                  Cockcroft-Gault equation (Men: CrCl (min/ml) = (140-age) X (actual weight in kg)
                  / 72 X serum creatinine (mg/dL); Women: CrCl (ml/min) = (140-age) X (actual
                  weight in kg) X 0.85 / 72 X serum creatinine (mg/dL))

          -  Woman of reproductive potential must agree to use highly effective methods of birth
             control during the period of therapy and for 30 days after the last dose of the study
             drug. Men who are sexually active must agree to use highly effective contraception
             during the period of therapy and for 3 months after the last dose.

          -  Female subjects of childbearing potential must have a negative plasma pregnancy test
             upon study entry. See section on Pregnancy and Reproduction.

          -  Patients must be able to tolerate MRI/CT scans.

          -  Patients must be able to tolerate lumbar puncture and/or Ommaya taps.

          -  Participants must have recovered to grade 1 toxicity from prior therapy.

          -  Participants should be able to submit up to 20 unstained formalin-fixed,
             paraffinembedded (FFPE) slides from the initial tissue diagnosis prior to study
             registration for confirmation of diagnosis and correlative studies

          -  All study participants must be registered into the mandatory Revlimid REMS® program,
             and be willing and able to comply with the requirements of the REMS® program.

          -  Females of reproductive potential must adhere to the scheduled pregnancy testing as
             required in the Revlimid REMS® program.

        NOTE: Prior autologous stem cell transplant as well as prior radiation to the CNS does NOT
        prevent patients from enrollment into the trial.

        Exclusion Criteria:

          -  Patients with SCNSL actively receiving treatment for extra-CNS disease are excluded.

          -  Patient is concurrently using other approved or investigational antineoplastic agents.

          -  Patient has received chemotherapy, monoclonal antibodies or targeted anticancer
             therapy ≤ 4 weeks or 5 half-lives, whichever is shorter, or 6 weeks for nitrosourea or
             mitomycin-C prior to starting the study drug, or the patient has not recovered from
             the side effects of such therapy.

          -  Patient has received external beam radiation therapy to the CNS within 21 days of the
             first dose of the study drug.

          -  Patient requires more than 8 mg of dexamethasone daily or the equivalent

          -  Patient has an active concurrent malignancy requiring active therapy

          -  The patient has been treated with radio- or toxin-immunoconjugates within 70 days of
             the first dose of the study drug.

          -  Patient is allergic to components of the study drug.

          -  Patient is using warfarin or any other Coumadin-derivative anticoagulant or vitamin K
             antagonists. Patients must be off warfarin-derivative anticoagulants for at least
             seven days prior to starting the study drug. Low molecular weight heparin is allowed.
             Patients with congenital bleeding diathesis are excluded.

          -  Patient is taking a drug known to be a moderate and strong inhibitor or inducers of
             the P450 isoenzyme CYP3A. Participants must be off P450/CYP3A inhibitors and inducers
             for at least two weeks prior to starting the study drug.

          -  Patient is using systemic immunosuppressant therapy, including cyclosporine A,
             tacrolimus, sirolimus, and other such medications, or chronic administration of > 5
             mg/day or prednisone or the equivalent. Participants must be off immunosuppressant
             therapy for at least 28 days prior to the first dose of the study drug.

          -  Patient has significant abnormalities on screening electrocardiogram (EKG) and active
             and significant cardiovascular disease such as uncontrolled or symptomatic
             arrhythmias, congestive heart failure, hypertension, valvular disease, pericarditis,
             or myocardial infarction within 6 months of screening,

          -  Patient has a known bleeding diathesis (e.g. von Willebrand"s disease) or hemophilia.

          -  Patient is known to have human immunodeficiency virus (HIV) infection.

          -  Patient is known to have a history of active or chronic infection with hepatitis C
             virus (HCV) or hepatitis B virus (HBV) as determined by serologic tests.

          -  Patient is known to have an uncontrolled active systemic infection.

          -  Patient underwent major systemic surgery ≤ 4 weeks prior to starting the trial
             treatment or who has not recovered from the side effects of such surgery, or who plan
             to have surgery within 2 weeks of the first dose of the study drug.

          -  Patient is unable to swallow capsules or has a disease or condition significantly
             affecting gastrointestinal function, such as malabsorption syndrome, resection of the
             stomach or small bowel, or complete bowel obstruction.

          -  Patient has poorly controlled diabetes mellitus with a glycosylated hemoglobin >8% or
             poorly controlled steroid-induced diabetes mellitus with a glycosylated hemoglobin of
             >8%. (for patients who received a short-term, high-dose dexamethasone treatment course
             prior to enrollment (<7 days), the HbA1c value can be rounded to the nearest whole
             number).

          -  Patient has a life-threatening illness, medical condition, or organ system dysfunction
             that, in the opinion of the investigator, could compromise the subject"s safety or put
             the study outcomes at undue risk.

          -  Women who are pregnant or nursing (lactating), where pregnancy is defined as a state
             of a female after conception until the termination of gestation, confirmed by a
             positive serum hCG laboratory test of > 5 mIU/mL (See section on Pregnancy and
             Reproduction)

          -  Patient has undergone prior allogenic stem cell transplant (autologous stem cell
             transplant is NOT an exclusion)

          -  The patient is unwell or unable to participate in all required study evaluations and
             procedures

          -  Known hypersensitivity to ibrutinib, thalidomide or lenalidomide

          -  Females who are pregnant.