Role of immunological lymphocyte subset typing as a screening method for lymphoid malignancies in daily routine practice

Background: The major diagnostic role of peripheral lymphocyte subset typin g is to distinguish between malignant and reactive conditions, Methods: The present study evaluates the screening efficacy of flow cytomet ric lymphocyte subset typing for the presence of a lymphoid malignancy. Fou r hundred samples were analyzed with a combination of anti-T-, B-, and natu ral killer (NK)-cell monoclonal antibodies. Results: Two hundred and twenty (55%) samples showed a normal distribution of lymphocyte subsets, 73 (18%) samples exhibited unspecific alterations of lymphocyte subsets, 19 (5%) samples exhibited a reactive phenotype typical of Epstein-Barr virus/cytomegalovirus (EBV/CMV) infection, and 88 (22%) sa mples expressed a phenotype suggestive of lymphoma. The most predictive ind ependent factor of a lymphoma-specific phenotype was the absolute lymphocyt e count (P = 0.0001, odds ratio 73.225), Seventy-eight percent of samples c ontaining greater than or equal to 4 x 10(9)/l lymphocytes and 2% of sample s with lymphocyte counts <4 x 10(9)/l exhibited a lymphoma-specific phenoty pe, The specificity of the referring clinical comment was the second best p redictor of a lymphoma-specific typing outcome (P = 0.0001, odds ratio 19.5 89), The independent predictive values of lymphocyte morphology and of rela tive lymphocyte counts were of borderline significance. Conclusions: The use of flow cytometric lymphocyte subset typing as a diagn ostic screening method for lymphoma should be restricted to cases of unexpl ained elevation of absolute lymphocyte counts with or without morphological atypias and to cases with definite clinical symptoms of lymphoma. (C) 2000 Wiley-Liss, Inc.