-  INCLUSION CRITERIA:

          -  Subjects must have histologically or cytologically confirmed EBV-positive LPD or an
             EBV-positive NHL confirmed by the Laboratory of Pathology, NCI.

               -  EBV-positive LPD. Subjects may be previously untreated or relapsed from prior
                  therapy.

                    1. Lymphomatoid granulomatosis (LYG), grades I-II

                    2. Chronic active EBV disease (CAEBV) of B-cells or T-cells

                    3. EBV-positive post-transplantation lymphoproliferative disorder (PTLD)

                       NOTE: PTLD after solid organ transplantation is excluded. Patients who, at
                       the discretion of the investigator, need urgent therapy with standard agents
                       will not be eligible.

               -  EBV-positive B-cell NHL. Subjects must have relapsed from previous treatment with
                  an anthracycline and rituximab-based regimen or be considered not eligible for
                  the same.

                    1. Lymphomatoid granulomatosis (LYG), grade III

                    2. EBV-positive immunodeficiency-associated diffuse large B-cell lymphoma
                       (DLBCL)

                    3. EBV-positive DLBCL

          -  Subjects must be at least 2 weeks from prior anti-lymphoma therapy (including
             radiation therapy)

          -  Subjects must be at least 100 days from prior stem cell transplant (autologous or
             allogeneic) or Donor Lymphocyte Infusion (DLI)

               -  Age greater than or equal to 12 years

               -  Patients greater than or equal to 12 and less than 18 years of age should weigh
                  at least 40 kilograms (kg); there is no weight requirement for adult subjects.

               -  NOTE: If a pediatric patient is identified for possible enrollment who weighs
                  less than 40 kg, the safety of the nivolumab dosing strategy used in this study
                  must be discussed with the PI and manufacturer to confirm safety, and this
                  discussion/approval for enrollment documented in the medical record prior to
                  declaring the pediatric patient eligible.

          -  Adequate performance status as follows:

               -  Patients greater than or equal to 16 years must have ECOG Performance Status 0-2
                  (Karnofsky greater than or equal to 60%)

               -  Pediatric patients less than 16 years must have Lansky play-performance of
                  60-100%

          -  Subjects must have measurable or evaluable disease.

          -  Subjects must have adequate organ and bone marrow reserve (unless disease-related) as
             defined below:

               -  absolute neutrophil count - greater than or equal to 750/mcL; greater than or
                  equal to 500/mcL if impairment is due to LPD/NHL

               -  platelets - greater than or equal to 50,000/mcL; greater than or equal to
                  25,000/mcL if impairment is due to LPD/NHL; (transfusions not permitted)

               -  Hemoglobin greater than or equal to 9g/dL (transfusion permitted)

               -  total bilirubin - < 3.0g/dl OR < 5.0g/dl if Gilbert s syndrome or disease
                  infiltration of the liver is present

               -  AST(SGOT)/ALT(SGPT) - less than or equal to 3 X institutional upper limit of
                  normal

               -  serum creatinine OR creatinine clearance - Adults: less than or equal to 1.5
                  mg/dL; Minors: serum Cr less than or equal to age-adjusted normal OR greater than
                  or equal to 40 ml/min/1.73m^2

          -  A formalin fixed tissue block or at least 15 slides of tumor sample (archival or
             fresh) must be available for performance of correlative studies. NOTE: Patient must be
             willing to have a pre-treatment tumor biopsy if adequate archival tissue is not
             available.

          -  The toxicity profile of nivolumab in patients with disease involvement of the central
             nervous system (CNS) is unknown. For this reason, we will introduce early stopping
             rules.

          -  The effects of nivolumab on the developing human fetus are unknown. For this reason,
             the following measures apply:

               -  Women of childbearing potential (WOCBP) must have a negative serum or urine
                  pregnancy test (minimum sensitivity 25 IU/L or equivalent units of HCG) during
                  screening and within 48 hours prior to the first dose of nivolumab.

               -  WOCBP and men who are sexually active with WOCBP must use adequate contraception
                  (e.g., hormonal or 2 barrier methods with a failure rate of less than 1% per year
                  or abstinence) prior to study entry and throughout study drug administration.
                  WOCBP receiving nivolumab will be instructed to adhere to contraception for a
                  period of 23 weeks after the last dose of investigational product. Men receiving
                  nivolumab and who are sexually active with WOCBP will be instructed to adhere to
                  contraception for a period of 31 weeks after the last dose of investigational
                  product.

               -  Women who are not of childbearing potential (i.e., who are postmenopausal or
                  surgically sterile as well as azoospermic men do not require contraception.

               -  WOCBP is defined as any female who has experienced menarche and who has not
                  undergone successful surgical sterilization (hysterectomy, bilateral tubal
                  ligation, or bilateral ophorectomy), and who is not postmenopausal. Post
                  menopause is defined as:

                    1. Amenorrhea greater than or equal to 12 consecutive months without another
                       cause, and a documented serum follicle stimulating hormone (FSH) level > 35
                       mIU/mL or

                    2. Women with irregular menstrual periods and a documented serum follicle
                       stimulating hormone (FSH) level > 35 mIU/mL or NOTE: FSH level testing is
                       not required for women greater than or equal to 62 years old with amenorrhea
                       of greater than or equal to 1 year

                    3. Women on hormone replacement therapy (HRT)

          -  Pregnant women are excluded from this study because nivolumab is an IgG monoclonal
             antibody with the potential for teratogenic or abortifacient effects.

          -  Because there is an unknown but potential risk for adverse events in nursing infants
             secondary to treatment of the mother with nivolumab, breastfeeding should be
             discontinued if the mother is treated with nivolumab.

          -  Ability of subject or Legally Authorized Representative (LAR) to understand and sign
             the written informed consent document.

        EXCLUSION CRITERIA:

          -  Subjects who are receiving any other investigational agents.

          -  History of allergic reactions attributed to compounds of similar chemical or biologic
             composition to nivolumab.

          -  Subjects with second malignancies requiring active systemic therapy are excluded.
             Subjects with second malignancies not requiring active systemic therapy or
             premalignant conditions such as monoclonal B-cell lymphocytosis (MBL) or monoclonal
             gammopathy of undetermined significance (MGUS) may be eligible.

          -  Subjects with any condition or autoimmune disease that requires systemic
             corticosteroids (> 10 mg daily prednisone equivalents) or immunosuppressive
             medications within 14 days of study drug administration. Inhaled or topical steroids
             are permitted.

          -  Subjects with active graft-vs-host disease (GVHD) requiring steroids or other
             immunosuppressive agents; history of greater than or equal to grade II acute GVHD or
             extensive chronic GVHD.

          -  Subjects who have had solid organ transplant.

          -  Prior therapy with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137 or anti CTLA-4
             antibody.

          -  Non-oncology vaccine therapies for prevention of infectious disease within 4 weeks of
             study drug administration.

          -  A serious uncontrolled medical condition requiring therapy.

          -  Seizures disorder not controlled by anti-seizure medications.

          -  Subjects with CNS involvement may be included on the study as long as they have not
             had any seizure activity in past 4 weeks.

          -  Hepatitis B virus surface antigen positive.

          -  Active Hepatitis C infection with a positive PCR; subjects who are Hepatitis C
             antibody positive and PCR negative may be eligible. In these cases the subjects will
             be monitored via HCV PCR throughout the study.

          -  History of anaphylactic reaction to monoclonal antibody therapy.

          -  HIV positive subjects are excluded because the function of their T-cell immune
             responses is impaired.