Janus Kinase Inhibition in Granuloma Annulare

Inclusion Criteria: Written informed consent Male and female patients 18 years old or older Diagnosis of GA with supportive skin biopsy BSA involvement of at least 5% 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 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® Tuberculosis 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 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 moderate to strong 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