PERIPHERAL T-CELL LYMPHOMA WITH HELPER T-CELL PHENOTYPE (LEU 3a+ LEU 8−)

Eleven cases of Leu 3a⁺ Leu 8^? peripheral T-cell lymphoma (PTCL), excluding adult T-cell leukemia/lymphoma, were studied by Immunostalning with monoclonal antibodies and enzyme histochemistry in order to clarify the histogenesis of PTCL. Seven of the eleven cases had varying degrees of polyclonal hypergammaglobulinemia. All cases were histologically characterized by neoplastic proliferation of clear cells and some cases showed a histologic background similar to IBL or AILD lesions with proliferation of 1m-munoblasts or plasmacytoid cells and vascular proliferation. Immunohis-tologic analysis of PLP-flxed frozen tissues revealed that neoplastic clear cells expressed a Leu 3a⁺ Leu 8^? phenotype (helper T-cell subset). The distribution of Leu 3a⁺ Leu 8'neoplastic cells corresponded closely to that of DRC-1⁺ cells, which are localized in the lymphatic follicles, but hardly at all with that of β-glucuronidase⁺ vessels, termed PCV or HEV, which are usually present in T-cell areas. One case only progressed from Leu 3a⁺ Leu 8^? IBL-like T-cell lymphoma (IBL-T), with proliferation of immunoblasts or plasmacytoid cells and vascular proliferation, to diffuse lymphoma of the large cell type showing none of these lesions. From these observations it is suggested that IBL-T might progress to T-cell-type monomorphous diffuse lymphoma.