Inclusion Criteria:
* Patients 18 years and older with refractory cutaneous symptoms related to either classic dermatomyositis (CD), juvenile dermatomyositis (JD), or amyopathic dermatomyositis (AD). Diagnosis will be based on either Bohan and Peter criteria (CD and JD) or Sontheimer's criteria (AD) (19-22).
* Patients must have had a skin biopsy with histologic features consistent with dermatomyositis and current cutaneous manifestations consistent with dermatomyositis.
* Patients will be considered to have refractory disease if cutaneous manifestations exist despite treatment with systemic corticosteroids and at least one steroid-sparing systemic treatment commonly found to be useful in patients with dermatomyositis. These may include azathioprine, cyclosporine, mycophenolate mofetil, IVIG, methotrexate, hydroxychloroquine, cyclophosphamide, chlorambucil, sirolimus, tacrolimus, and rituximab.
* Patients must have sufficiently active cutaneous involvement of dermatomyositis (BSA\>1% to \<20%, CDASI activity score \> 6, and Physician Global Assessment (PGA) activity score \>2).
* Patients must have tried and failed at least one commonly prescribed topical medication in the past, with the last application of a topical medication to active skin lesions occurring greater than 2 weeks prior to enrollment.
o Commonly prescribed topical medications for dermatomyositis include corticosteroids or calcineurin inhibitors (tacrolimus or pimecrolimus).
* Patients must have been on a stable systemic medication regimen for at least 2 months (60 days) and must agree to keep the regimen stable throughout the study period. As patients with dermatomyositis are commonly treated with combination regimens that include both topical and systemic immunosuppressive medications, any added risk of adverse effects related to ruxolitinib 1.5% cream is considered negligible.
* Patients must be agreeable to use appropriate contraceptive measures while enrolled in the study.
* Women of childbearing potential must be willing to practice abstinence or use either an oral contraceptive medication or IUD if sexually active.
* Women of childbearing potential must be willing to have monthly urine pregnancy tests while enrolled in the study
* Men of childbearing potential must be willing to practice abstinence or use condoms if sexually active.
Exclusion Criteria:
* Patients with dermatomyositis who have minimal-to-no active cutaneous disease (mild involvement with \< 1% total body surface area involved and/or CDASI activity score of \< 6).
* Patients who have \> 20% total BSA involvement of cutaneous dermatomyositis.
* Patients who have used a common prescription topical medication within the previous 2 weeks.
* Patients whose cutaneous findings are not consistent with dermatomyositis and/or have previous biopsy results suggestive of an alternative diagnosis
* Patients not on stable systemic medication regimens for at least 2 months and/or who will not agree to keep the regimen stable throughout the study period.
* Patients who have previously taken a systemic Janus kinase inhibitor but had a poor response, patients who are currently taking systemic Janus kinase inhibitors, or patients who have used a topical Janus kinase inhibitor for their dermatomyositis or any other condition and had poor responses.
* Patients with inflammatory myositis other than dermatomyositis, such as polymyositis or inclusion body myositis.
* Patients with clear features of an overlap autoimmune myositis or with an inflammatory myositis not consistent with dermatomyositis, such as polymyositis or inclusion body myositis.
* Patients with an active malignancy other than non-melanoma skin cancer, or with malignancy-associated dermatomyositis.
* Patients younger than 18 years old
