Immunophenotyping of low-grade B-cell lymphoma in blood and bone marrow: poor correlation between immunophenotype and cytological/histological classification.

Results of immunophenotypic examinations of peripheral blood and/or bone marrow (BM), involved in low-grade B-cell non-Hodgkin's lymphomas, were compared with the results of cytomorphological and histopathological examinations in 133 adult patients. 69 cases of chronic B-lymphocytic leukaemia (B-CLL), 16 centrocytic (CC) lymphomas, 14 centroblastic-centrocytic (CB/CC) lymphomas, 15 immunocytomas (IC), 10 cases of hairy cell leukaemia (HCL), four prolymphocytic leukaemias (PLL), two B-CLL in transformation, one splenic lymphoma with villous lymphocytes (SLVL), one hairy cell leukaemia variant (HCL-V), and one lymphocytic lymphoma (LC) were classified according to the Kiel and/or FAB classification. Leukaemic disease was found in 105 cases. The following markers were used for immunocytology (APAAP technique) of blood and/or BM smears: CD19, CD5, CD10, CD11c, CD14, CD21, CD22, CD23, CD25, CD38 and TdT. All cases tested showed CD19, but no TdT expression. Every case of HCL had a distinct phenotype with expression of CD11c, CD22 and CD25 and the lack of CD5 and CD23 antigens. In all other NHL cases a very heterogenous expression of CD-antigens with no significant correlations to the cytomorphological subtypes was found. The expression of CD5 is a frequent but inconstant finding in lymphoproliferative diseases other than B-CLL, so 50% of CB/CC, 75% of CC and 80% of IC were CD5 positive. Our results indicate that, with the exception of HCL, the diagnostic relevance of immunophenotyping for the classification of cytomorphologically and histopathologically defined subtypes in blood and/or BM is of very limited value.