Peripheral T-cell lymphomas (PTCLs) are rare and heterogeneous non-Hodgkin lymphomas that have been separated by clinical presentation, histology, immunohistochemistry markers, infectious agents, and genetic abnormalities. They may have extranodal dissemination and are often aggressive, especially when they express cytotoxic markers. The international T-cell Non-Hodgkin Lymphoma Study Group collaboration has highlighted differences in the frequency of these entities in different geographic areas.[1,2] For example, HTLV-1+ adult T-cell lymphomas are found in Japan and nasal NK/T-cell lymphoma occurs predominantly in Asian countries. The most common PTCLs are unique and not able to be classified by a specific marker or tumor antigen, and are known as peripheral T-cell lymphomas, not otherwise specified (PTCL-NOS).
Madeleine Duvic, MD
There are few approved therapies for cutaneous T-cell lymphoma (CTCL). The retinoids are the major biologic response modifiers used in CTCL, producing good response rates but few complete responses. For patients with early-stage disease, the oral retinoids can be combined with other therapies, such as psoralen plus ultraviolet A or interferon α, to improve response rates. Combined-modality therapy with oral retinoids, combined chemotherapy, electron-beam therapy, and topical mustargen has also proved effective. For the treatment of advanced-stage disease, the targeted therapy denileukin diftitox (Ontak) provides a nonimmunosuppressive alternative to conventional chemotherapy or radiation therapy. Of the conventional chemotherapies that have been tested in CTCL, gemcitabine (Gemzar) has demonstrated good efficacy in producing responses, particularly in patients with tumors. This agent can be used in combination with a maintenance therapy of bexarotene (Targretin) to manage the plaques and patches of mycosis fungoides. Several other targeted therapies are now also in testing, for example, alemtuzumab (CamPath), HuMax-CD4, several histone deacetylase inhibitors, and the transition-state inhibitor forodesine. These drugs, in combination with currently used therapies, may increase the number and combinations of therapies available for the treatment of this chronic condition to optimize long-lasting responses in CTCL.