Immunophenotypic analysis of non-Hodgkin's lymphomas in cytologic specimens: A correlative study of immunocytochemical and flow cytometric techniques

Most Non-Hodgkin's lymphomas(NHL) can be accurately diagnosed and classifie d based on morphologic and immunophenotypic findings on cytologic specimens . Immunophenotyping can be accomplished via immunocytochemistry (IC) or flo w cytometry (FC). We reviewed our experience with 98 cytology specimens (70 fine-needle aspirates [FNA] and 28 effusions) that were submitted for immu nophenotyping utilizing both IC and FC between January 1992 and December 19 97 for the diagnosis of NHL. Eighty-five percent of the cases were immunoph enotyped by both techniques. Among these there were only two discrepancies between IC and FC, yielding a 98% correlation rate. Of the 98 cases, 11% co uld nor be immunophenotyped by FC and 4% could not be immunophenotyped by I C. The advantage of IC is the preservation of cytomorphology, which results in the requirement for a lower number of neoplastic cells and a limited, t argeted panel of antibodies. This is especially useful in predominantly nec rotic lymphomas in which only a few well-preserved neoplastic cells may he present, rendering the specimen inadequate for immunophenotyping by FC. The advantages of FC are in the detection of A small population of monoclonal cells in a background of reactive cells (particularly useful in effusion sa mples in which the predominant cell population is often reactive T lymphocy tes), increased diagnostic precision through evaluation of objective parame ters, and the use of multiple markers with dual labelling. We conclude that IC and FC are both excellent methods for immunophenotyping of cytology spe cimens and can be used interchangeably depending oil the institutional expe rtise and availability. Diagn. Cytopathol. 1999;20:278-284. Published 1999 Wiley-Liss, Inc.