Study of Ruxolitinib in Relapsed or Refractory T or NK Cell Lymphoma

Inclusion Criteria: * Pathologically confirmed T or NK cell lymphoma at the enrolling institution. For CTCL, patients with stage IB disease or greater are eligible. * Relapse or refractory disease after at least 1 systemic therapy except for T-PLL, LGL, or T-cell Lymphoproliferative diseases with JAK2 fusion. * Untreated patients may be allowed after discussion with P.I. * Age ≥ 18 * ECOG ≤ 2 * Measurable disease defined by: * Lugano Classification for systemic lymphoma or * Atypical and or malignant lymphocytes quantifiable by flow cytometry or morphology in blood or bone marrow or * mSWAT \> 0 or Sezary count ≥ 1000 cells/μL for CTCL * Previous systemic anti-cancer therapy for T-cell lymphoma must have been discontinued at least 2 weeks prior to treatment. * Glucocorticoids aimed at controlling lymphoma-related symptoms are allowed as long as they are tapered down to 20mg or less by the time of ruxolitiib initiation * Topical steroids for CTCL are permitted * See section 6.2 Subject Exclusion Criteria for guideline regarding adjuvant and maintenance therapy for prior malignancy * Patients must meet the following lab criteria: * ANC ≥ 1.0/mm\^3 or ANC \>/= 0.5/mm\^3 (if patient has baseline neutropenia due to lymphoma), platelets ≥ 100 x 10\^9/L or ≥ 50 x 10\^9/L (if related to lymphoma), Hgb ≥ 8g/dL * Patients with LGL or T-PLL are not required to meet a minimum ANC or hemoglobin value for eligibility * Total bilirubin ≤ 1.5 x upper limit of normal (UL…