Recalcitrant Subcutaneous Panniculitis-Like T-Cell Lymphoma Responsive to Histone Deacetylase Inhibitor.

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare subtype of cutaneous T-cell lymphoma that usually presents with tender subcutaneous nodules on the trunk and extremities. Immunosuppressive therapy is considered first-line treatment for SPTCL, while multiagent chemotherapy is used for SPTCL complicated by hemophagocytic lymphohistiocytosis (HLH). Here, we report a 42-year-old Hispanic man that presented with a 5-year history of recurrent painful subcutaneous lesions in the absence of constitutional symptoms, lymphadenopathy, and hepatosplenomegaly. A punch biopsy revealed an atypical lymphoid infiltrate in between subcutaneous adipose lobules. Lymphocytes expressed CD3, CD8, and Beta F-1 and did not express CD4 and CD56. Based on clinical and histologic findings, the patient was diagnosed with SPTCL. In addition, laboratory findings did not demonstrate any evidence of HLH. He was initially started on both prednisone and hydroxychloroquine with no improvement. A trial of cyclosporine and methotrexate yielded no clinical improvement. As the lesions failed to resolve after treatment with multiple immunosuppressive agents, romidepsin, an intravenous histone deacetylase (HDAC) inhibitor, was initiated. After two cycles of romidepsin, the patient achieved complete clinical response. He continues to be in remission 12 months later with monthly maintenance therapy. This case illustrates that romidepsin can be useful as monotherapy for refractory SPTCL without HLH.