FLOW CYTOMETRIC STUDIES ON LYMPH-NODES : THE POTENTIAL IMPACT ON THE DIAGNOSIS OF LYMPHOPROLIFERATIVE DISORDERS.

* M. Lima, * A.H. Ribeiro dos Santos, * L. Xavier , * A . Pinto Ribeiro, * J . Coutinho, ** A.L. Canelhas **F.A. Silvestre, **C. Peixoto, **C.Barbedo, ** J.M. Cabral, **S. David, **A. Paiva *B. Justiça.

*Service of Hematology and

** Service of Pathology, St. António's Hospital, Porto, Portugal.

Introduction: The investigation of patients with lymphoproliferative disorders (LPD) includes histological and immunophenotypic analysis of lymph node (LN) biopsies. This is usually performed by classic immunohistochemical (IH) methods, flow cytometric (FC) studies being rarely used in this case. The present study was aimed to evaluate the usefulness of routine immunophenotyping LN biopsies by FC in the diagnosis of patients with LPS.

Material and Methods: FC was performed on cell suspensions obtained from fresh LN from patients with clinically suspected or previously diagnosed lymphoma. The following monoclonal antibodies were used in the first approach, applying the following double stainings : CD14/CD45, CD2/CD19, CD8/CD4, HLA-Dr/CD3, þ /þ immunoglobulin light chains. Other B, T, NK or other cell markers were used when indicated.

Results : We present illustrative examples of reactive and neoplastic LPD disorders whose LN were studied by FC and classic IH. The results obtained by FC were complementary to those obtained by IH. Reactive hyperplasias had polimorphic and polyclonal lymphoid populations. B-cell lymphomas usually showed a more monotonous population with an aberrant monoclonal B-cell phenotype, although variable proportions of reactive T cells were frequently found. T-cell lymphomas were usually identified by an abnormal immature or aberrant T-cell immunophenotype.

Comments : FC has the great advantage of permitting a rapid analysis and more accurate characterization of large numbers of cells, having a great potential for the study of LN in patients with LPD. However the immunophenotyping data should be always complemented with the histology in order to prevent misdiagnosis and to maximize the information obtained.