Tyrosine Kinase 2 (TYK2) for GA and CS

Inclusion Criteria: * Written informed consent * Male and female patients 18 years old or older * Diagnosis of GA or cutaneous sarcoidosis with supportive skin biopsy * BSA involvement of at least 5% (GA) or CSAMI numerical score of at least 10 (sarcoidosis) * If patients are on systemic therapies or phototherapy for their GA, they must discontinue these therapies with a washout period of 4 weeks and must remain off them during the study * If patients are on topical therapies for their GA, they must discontinue these therapies with a washout period of 2 weeks and must remain off them during the study * If patients are taking other systemic therapies for their sarcoidosis, they must be taking a stable dose of the other medication(s) for at least 3 months with no plans to change the regimen in the next 6 months. With the exception of methotrexate or low dose prednisone (20 mg or less per day), use of concomitant immunosuppressants, e.g. infliximab, azathioprine, etc., will not be permitted. * For sarcoidosis, washout of topical medications will be for 2 weeks. * Washout for oral medications will not be possible in most cases. Patients will be allowed to continue concomitant prednisone (up to 20 mg daily) or weekly methotrexate (up to 15 mg daily). * Females of childbearing potential must agree to use birth control during the study and there must be a negative pregnancy test documented prior to starting the medication. * Patients must be willing to have skin biopsies, blood collection, and total body photography and to comply with clinic visits Exclusion Criteria: * Age \<18 years old * Patients with a history of malignancy (except history of successfully treated basal cell or squamous cell carcinoma of the skin) * Patients known to be HIV or hepatitis B or C positive, or have an active, serious infection herpes simplex, herpes zoster, and pneumonia. This would also include localized infections. * Patients with positive tuberculin skin test or positive QuantiFERON® TB test * Patients with significant hepatic impairment * Patients with moderate renal impairment * Patients with uncontrolled peptic ulcer disease * Patients with a history of deep vein thrombosis and/or pulmonary embolism and/or clotting disorder * Patients with any history of myocardial infarction or stroke. * Patients taking concomitant immunosuppressive medications, with the exception of methotrexate and/or low-dose prednisone, including but not limited to mycophenolate mofetil, azathioprine, tacrolimus, cyclosporine, or TNF-α inhibitors * Women of childbearing potential who are unable or unwilling to use birth control while taking the medication * Women who are pregnant or nursing * Current smoker or history of any tobacco use * Patients over 50 who have the presence of cardiovascular risk factor * Screening labs outside the normal range for parameters associated with potential risk for treatment under investigation. Including but not limited to: i. Platelets \<150,000/mm3, ii. Absolute neutrophil count \<1,000/mm3, iii. Hemoglobin levels \<8 g/dL, iv. Absolute lymphocyte count \<500/mm3 * Patients who are taking clinically significant inhibitors of both CYP2C19 and CYP2C9, or strong CYP2C19 or CYP2C9 inducers, as well as P-gp substrate where small concentration changes may lead to serious or life-threatening toxicities. * Patients who have received a live vaccine. Patients should wait a minimum of 2 weeks, if recently vaccinated, prior to initiating treatment and should not receive a live vaccine during treatment or 2 weeks post-treatment. * Patients with any medical, psychiatric, or social condition that is likely to unfavorably affect the risk-benefit of continued study participation, interfere with study compliance or confound safety or efficacy assessments