Patient description: The patient is a 60 year old man complaining of frequent headaches, generalized bone pain and difficulty chewing that started 6 years ago and is worsening. Examination shows bilateral swellings around the molars. The swellings have increased since his last examination. Several extraoral lesions are detected in the head and face. The swellings are non-tender and attached to the underlying bone. Further evaluation shows increased uptake of radioactive substance as well as an increase in urinary pyridinoline. His serum alkaline phosphatase is 300 IU/L (the normal range is 44- 147 IU/L). His family history is only significant for hypertension in his mother and DM type 2 in his father. The diagnosis of Paget's Disease of Bone was confirmed and Bisphosphonate will be started as first-line therapy.

Clinical trial eligibility criteria: eligible ages (years): 18.0-80.0,  Crohn Disease Subject has provided informed consent. 2. Male or female subjects, 18 to 80 years of age, inclusive. 3. Prior diagnosis of CD confirmed by endoscopy or imaging for > 3 months prior to enrollment with active disease, defined as a Crohn's Disease Activity Index (CDAI) score >220 to <450 and at least one of either: fecal calprotectin >250 ug/g feces, or CRP >8 mg/L. 4. Patients will have evidence of ileocolonic, colonic, or ileal disease that is visualized either endoscopically or on MRI within the prior 6 months. 5. Patients must carry at least one G allele at rs2062305. 6. Patients will be eligible for the study if they are receiving any of the following mesalamine for >8 weeks with the dose remaining stable for 4 weeks prior to screening a maximum of 20 mg of prednisone per day (or steroid equivalent), with the dose remaining stable for 2 weeks prior to screening. Steroids must be held stable for the first 4 weeks of the study and then must be tapered by 5 mg per week, to be discontinued entirely by week 8 mercaptopurine, methotrexate or azathioprine for ≥3 months, with the dose remaining stable for 8 weeks prior to screening  Monoclonal antibody or experimental agent use within 12 weeks before screening. 2. Use of non-approved drugs for CD. 3. Anticipated need for surgery within 12 weeks 4. Active sepsis, or use of antibiotics within two weeks prior to screening for the treatment of infection. 5. Pregnant, lactating or planning to become pregnant during the study 6. Inability to reliably use birth control for men and women during the course of therapy. 7. Known allergy to Denosumab or ingredients in formulation 8. Treatment of cancer within the last 5 years (except for non-melanoma skin cancers). 9. Recent jaw infection, invasive dental procedures (tooth extraction, dental implants or surgery), anti-angiogenic medications, or hypocalcemia within 1 month prior to screening. 10. Patients will also be excluded if they meet any of the following Proctocolectomy or total colectomy; stoma; a history of allergy to murine proteins; or treatment with parenteral corticosteroids or corticotropin within four weeks before screening. Serum Hg < 80 g/L, liver enzymes ≥ 2-fold elevated, or other serum biochemistry considered unsafe, or requiring treatment, in the opinion of the investigator