Peripheral T-cell lymphomas are a collection of
rare diseases, most of which have a poor prognosis. The basic categories include precursor lymphoid
neoplasms (eg,
lymphoblastic lymphoma); mature natural killer/T-cell
neoplasms and extranodal
lymphomas, including
enteropathy-associated T-cell lymphoma; hepatosplenic
T-cell lymphoma; and
subcutaneous panniculitis-like T-cell lymphoma. The most common varieties are the nodal types, which include
peripheral T-cell lymphoma not otherwise specified,
anaplastic large cell lymphomas, and angioimmunoblastic
T-cell lymphomas. Each of the subtypes has characteristic clinical manifestations. The frequencies of the subtypes vary by geographic region. The diagnosis can be difficult, and the World Health Organization classification system was recently evaluated to assess its clinical applicability and reproducibility for
peripheral T-cell lymphomas and natural killer/T-cell
lymphomas. At least 10% of patients are incorrectly diagnosed by local laboratories, and many subtypes need better diagnostic markers and criteria. Currently, an increasing number of effective and tolerable
therapies are becoming available, including
pralatrexate,
brentuximab vedotin,
romidepsin, and
bendamustine. Accurate diagnosis is necessary to allow appropriate treatment, as exemplified by patients with
anaplastic large cell lymphoma that expresses high levels of CD30, who have high response rates to
brentuximab vedotin. Patients with
peripheral T-cell lymphoma should be enrolled in clinical trials when possible. New medications should be incorporated into
therapies in well-designed clinical trials to develop appropriate safety and efficacy data.