-INCLUSION CRITERIA:

          1. Surgically inoperable participants with clinical diagnosis of PHEO/PGL who also have
             demonstrated disease histologically consistent with pheochromocytoma or paraganglioma
             (preferably confirmed by research site pathology review if initial pathology was done
             outside of research site, but not mandatory).

          2. Progressive disease by RECIST with or without symptoms within the last 12 months.
             NOTE: Untreated participants with existing histologic diagnoses are eligible if
             progression can be demonstrated.

          3. PHEO/PGL that is not associated with any known susceptibility genetic mutations for
             PHEO/PGL except SDHx mutation (a.k.a. "apparent sporadic"), based on documented
             genetic testing results obtained prior to study enrollment. PHEO/PGL that is
             associated with non-SDHx mutations such as VHL, NF1, and RET will not be eligible for
             this study.

          4. Patient is or will be enrolled on protocol 00-CH-0093, Diagnosis, Pathophysiology, and
             Molecular Biology of Pheochromocytoma and Paraganglioma (NIH only).

          5. Both metastatic and inoperable primary-only participants are eligible.

          6. Must have presence of SSTR+ disease as documented by positive Ga-68-DOTATATE PET scan
             within 12 weeks of anticipated treatment.

             NOTE:

               -  Positivity of Ga-68-DOTATATE PET scan defined as having at least one lesion that
                  is greater than or equal to 10 mm in diameter with uptake that is higher than or
                  equal to liver and is qualitatively higher and distinguishable from background
                  activity.

               -  Measurable disease as defined by RECIST 1.1

          7. Age greater than or equal to 18

          8. Karnofsky Performance Score greater than or equal to 60 or ECOG Performance Status of
             2 or better.

          9. Able to understand and willings to sign informed consent

         10. Ability and willingness to obtain all required scans per study schedule.

         11. Negative serum pregnancy test for women of child bearing potential or NOTE: A female
             is not of childbearing potential if a prior history of hysterectomy with bilateral
             oophorectomy or other procedure has render the participant surgically sterile, or >2
             years since last menstruation.

         12. Female participants of childbearing potential and male participants who are not
             surgically sterile or with female partners of childbearing potential must agree to use
             effective, non-hormonal means of contraception (intrauterine contraceptive device,
             barrier method of contraception in conjunction with spermicidal gel) prior to study
             entry, for the duration of study participation and for 6 months (10 half-lives of
             Lu-177) after the last dose of Lu-177- DOTATATE.

         13. Must have outside endocrinologist/medical oncologist who can follow the participant
             after receiving PRRT (NIH only requirement).

         14. Patients with secreting tumors must be receiving adequate pharmacologic catecholamine
             blockade as determined by the treating physician.

         15. Ineligible, unable to or unwilling to receive standard first line therapy for
             PHEO/PGL.

        EXCLUSION CRITERIA:

          1. Creatinine clearance <50 mL/min calculated by the MDRD method, eventually confirmed by
             measured creatinine clearance (or measured glomerular filtration rate (GFR) using
             plasma clearance methods.

          2. Serum albumin less than or equal to 3.0 g/dL unless prothrombin time is within the
             normal range.

          3. Liver dysfunction as evidenced by Child s Class C Liver Disease or worse
             Alternatively, AST or ALT > 2.5 times institutional upper limit of normal (ULN) unless
             liver metastases are present, in which case up to 5 times ULN would be allowed.

          4. Hb < 8.0 g/dL; WBC < 2.0 x 10^9/L (or Absolute Neutrophil Count < 1000); Platelets <
             100 x 10^9/L

          5. In participants with symptoms of congestive heart failure, New York Heart Association
             (NYHA) classification of grade III or IV

          6. Pregnancy or lactation.

          7. Prior anti-tumoral radionuclide therapy with unsealed sources. Prior therapy with
             sealed radioactive sources such as brachytherapy will be allowed.

          8. Prior local radiation therapy would be allowed as long as there is at least one
             non-irradiated index lesions.

          9. Known brain metastases, unless these metastases have been treated and stabilized for
             at least 24 weeks, prior to enrollment in the study. Patients with a history of brain
             metastases must have a head CT or MRI scan with contrast to document stable disease
             for at least 24 weeks prior to enrolment in the study.

         10. Other known co-existing malignancies except non-melanoma skin cancer and carcinoma in
             situ of the uterine cervix, unless definitively treated and proven no evidence of
             recurrence for 5 years.

         11. Patients who participated in any therapeutic clinical study with an investigational
             agent within the last 30 days.

         12. Patients may be on somatostatin analogue therapy (e.g. but not only limited to
             sandostatin or lanreotide therapy). However, therapy with somatostatin analogues
             should not be initiated or altered within 3 months of study enrolment. Patients on
             short term octreotide may have dose held for 24 hours prior to Lu-177-DOTATATE
             therapy. Those on long acting octreotide therapy will receive treatment at 1 to 5 days
             prior to their next cold octreotide dose, in order to prevent competition for the
             receptor.

         13. Patient weight > 400 lbs (table limit for PET scanner) or per local institutional
             standard for non-NIH sites.

         14. Uncontrolled inter-current illness including, but not limited to, ongoing or active
             infection, symptomatic congestive heart failure, unstable angina pectoris,
             hypertension (>180/110), arrhythmia, or psychiatric illness/social situations that
             would limit compliance with study requirements.

         15. Inability to tolerate at least one modality of diagnostic anatomic imaging, such as CT
             or MRI.