ABSTRACT
Peripheral T-cell lymphoma (PTCL), not otherwise specified, is a heterogeneous group of tumors with variable clinical features, histology, genetic alteration, response to treatment, and prognosis. The distinction from other peripheral T-cell disorders is based on clinical, morphologic, phenotypic, and genetic data, but is not always clear, especially at the time of initial diagnosis. The International Prognostic Index appears to be the best current prognostic model in PTCL. Lymphopenia is an independent prognostic marker to predict an unfavorable overall survival in PTCL. Patients with PTCL have an extremely poor prognosis when relapsed or refractory to conventional chemotherapy. PTCLs may occur in extranodal sites, including the spleen, gastrointestinal tract, liver, skin, and soft tissues. The differential diagnosis of PTCL includes a wide variety of malignant and reactive lesions, which show either T-zone pattern of lymph node involvement or display cytomorphologic features that may histologically resemble PTCL.
