The role of gene rearrangements for antigen receptors in the diagnosis of lymphoma obtained by fine-needle aspiration: A study of 63 cases with concomitant immunophenotyping

To assess the efficacy of performing genotyping in addition to immunophenotyping as an adjunct to cytologic diagnosis, 63 consecutive patients with fine-needle aspirates of lymphoproliferative lesions who had concurrent immunophenotyping and genotyping performed on fine-needle aspirate cell suspensions were studied. Thirty-nine of 63 specimens (62%) that appeared to contain non-Hodgkin's lymphoma and that proved to be of Bcell lineage by genotyping were accurately phenotyped and shown to be monotypic for immunoglobulin light chains by cell suspension immunocytochemistry. Genotyping facilitated lineage assignment and/or confirmed clonality in 17 of 63 specimens (27%) that were difficult to determine based on morphologic data. These include cases of atypical lymphoid proliferations with polyclonal or inconclusive markers (n = 6), peripheral T-cell lymphoma (n= 3), extracutaneous mycosis fungoides (n = 1), lymphoblastic lymphoma (n = 4), null cell lymphoma (n = 1), and specimens with equivocal or technically unsatisfactory markers (n = 2). Based on these results, it is proposed that genotyping for lineage assignment and/or clonality be performed to include cases of atypical lymphoid proliferations, T-cell malignant neoplasms, lymphoid malignant neoplasms with equivocal markers, and differentiation of lymphoid from nonlymphoid neoplasms. Genotyping by antigen-receptor gene rearrangement appears to be redundant in cases with mature B-cell phenotypes that demonstrate monoclonality by immunophenotyping. (Key words: Fineneedle aspiration; Lymphoma; Gene rearrange