Key Points: Alternatively polarized macrophages are abundant constituents of the tumor microenvironment in T-cell lymphoproliferative disorders. GATA-3 expression identifies a subset of PTCL, NOS with a distinct cytokine profile and inferior survival.

Disease overview: Cutaneous T‐cell lymphomas are a heterogenous group of T‐cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).Diagnosis:The diagnosis of MF or SS requires the integration of clinical and histopathologic data.Risk‐adapted therapy: TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a “risk‐adapted,” multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin‐directed therapies is preferred, as both disease‐specific and overall survival for these patients is favorable. In contrast, patients with advanced‐stage disease with significant nodal, visceral, or blood involvement are generally approached with biologic‐response modifiers or histone deacetylase inhibitors before escalating therapy to include systemic, single‐agent chemotherapy. In highly‐selected patients, allogeneic stem‐cell transplantation may be considered, as this may be curative in some patients. Am. J. Hematol. 91:151–165, 2016.

Disease Overview: Cutaneous T‐cell lymphomas are a heterogenous group of T‐cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).Diagnosis: The diagnosis of MF or SS requires the integration of clinical and histopathologic data.Risk‐Adapted Therapy: TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a “risk‐adapted,” multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin‐directed therapies is preferred, as both disease‐specific and overall survival for these patients is favorable. In contrast, patients with advanced‐stage disease with significant nodal, visceral or the blood involvement are generally approached with systemic therapies, including biologic‐response modifiers, histone deacetylase inhibitors, or antibody‐based strategies, in an escalating fashion. In highly‐selected patients, allogeneic stem‐cell transplantation may be considered, as this may be curative in some patients.