Immunophenotypes in "well-differentiated" lymphoproliferative disorders, with emphasis on small lymphocytic lymphoma.

The histologic, immunophenotypic, and clinical findings in 24 cases of "well-differentiated" lymphoproliferative disorders are presented, with an emphasis on small lymphocytic lymphoma (SLL; well-differentiated lymphocytic lymphoma, WDLL). SLL was diagnosed in 18 patients, Waldenström's macroglobulinemia in one, mantle zone lymphoma (MZL) in four, and intermediate differentiated lymphocytic lymphoma (IDL) in one. Immunophenotypic analysis revealed one SLL to be of T-cell derivation, while a monoclonal B-cell phenotype was found in the remaining 23 patients; 20 of these neoplasms co-expressed the pan-T-cell antigen Leu-1. This included three of the four patients with MZL and the patient with IDL. All SLLs with pseudofollicular growth centers stained for transferrin receptor. Additionally, a survey of 248 non-Hodgkin's lymphomas of all types revealed four of 70 patients with B-cell large cell lymphoma (LCL; diffuse histiocytic lymphoma, DHL) that also co-expressed the same Leu-1 antigen. Immunoperoxidase study of both frozen tissue sections and cytocentrifuge preparations eliminated the limitations of faint antigen expression and/or interstitial immunoglobulin staining. In addition to detailing the immunophenotype of SLL, the immunologic kinship of MZL/IDL to SLL and the uncommon co-expression of Leu-1 in B-cell LCLs are demonstrated.