A group of malignant lymphomas thought to derive from peripheral t-lymphocytes in lymph nodes and other nonlymphoid sites. They include a broad spectrum of lymphocyte morphology, but in all instances express T-cell markers admixed with epithelioid histiocytes, plasma cells, and eosinophils. Although markedly similar to large-cell immunoblastic lymphoma (lymphoma, large-cell, immunoblastic), this group's unique features warrant separate treatment.