Flow cytometric analysis of deep-seated lymph nodes.

Flow cytometry (FC) immunophenotyping is an important tool in the evaluation of lymphadenopathy and is widely used in the diagnosis of non-Hodgkin's lymphomas (NHLs) on fine-needle aspirates of lymph nodes and extranodal sites. Because at least 80% of NHLs are of B-cell type, detection of immunoglobulin (Ig) light-chain-restriction is the most commonly used method for confirmation of monoclonality. The aim of our study was to evaluate usefulness of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) for FC analysis from deep-seated lymph nodes and to compare results of FC clonality analysis to cytomorphologic diagnosis of sampled lymph nodes. For cytological diagnosis direct smears were made, selected slide was stained for rapid-on site evaluation procedure. Sixteen patients with suspected NHL of deep-seated lymph nodes obtained by EUS-FNA were submitted for FC clonality analysis using four-color multiparameter flow cytometry stained with kappa/lambda/CD19/CD45. Clonality analysis was performed on 11 samples. Monoclonality was demonstrated in seven of 11 cases cytologically diagnosed as NHL and four of 11 cases cytologically diagnosed as benign were polyclonal. Our results show that EUS-FNAC with FC is a sensitive and specific tool in the diagnosis of deep-seated B-NHL. Cytologic diagnosis combined with FC clonality analysis can be performed in majority of cases and may eliminate need for open biopsy in some cases.