An immunocytochemical study of non-Hodgkin's lymphomas.

Lymph node specimens obtained intraoperatively and/or at autopsy from 89 patients with non-Hodgkin's lymphoma were studied immunohistochemically. The peroxidase anti-peroxidase (PAP) technique was used for detecting monoclonal cytoplasmic immunoglobulin (CIg) and for determining the classes and types of immunoglobulins in the tumors. Following rigid criteria, monoclonal CIg was demonstrated in four (16%) of 25 cases of nodular, poorly differentiated lymphocytic lymphoma (NPDL); in three (14%) of 21 cases of diffuse, poorly differentiated lymphocytic lymphoma (DPDL); and in 13 (30%) of 43 cases of diffuse histiocytic lymphoma (DH). Of the four NPDL patients, two had the M kappa, one the A kappa, and one the lambda chain type. Of the three DPDL patients, one had the M kappa, one the G kappa, and one the lambda chain type. Of the 13 DH patients, five had the M kappa, four the A kappa, one the GM kappa, one the A kappa, one the G kappa, and one the kappa chain type. In two DH patients negative for cytoplasmic immunoglobulins, cytoplasmic lysozyme was present, indicating the histiomonocytic nature of the tumor cells. There was no significant difference between the overall survival rates for the DH patients with or without monoclonal CIg. In all three types of lymphoma studied, we encountered many patients (67%) who had tumor cell populations without demonstrable CIg and few patients (11%) with polyclonal CIg. There are several possible reasons why many of the patients were PAP-negative and why some had polyclonal cell populations. The PAP method may be useful in establishing the monoclonal nature of neoplastic lymphoid cell populations.