Flow Cytometry as an Adjunct to Fine Needle Aspiration Cytology in the Diagnosis and Subtyping of Non-Hodgkin Lymphoma.

[INTRODUCTION] Fine needle aspiration cytology (FNAC) is widely used in the investigation of lymphadenopathy. FNAC in conjunction with flow cytometry (FCM) immunophenotyping has proven to be a fundamental tool in the diagnosis and subtyping of non-Hodgkin lymphoma (NHL). FCM is objective and offers multiparametric quantitative results and is very useful in assessing the clonality.

[AIM] To evaluate the diagnostic efficiencyof FNAC-FCM immunophenotyping in the definite diagnosis and classification of non-Hodgkin lymphoma.

[MATERIAL AND METHOD] This study retro-prospectively assessed 119 suspected cases of NHL which were diagnosed using FNAC-FCM. The FNAC-FCM diagnoses were correlated with the respective histopathology diagnoses (HPE) and sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated.

[RESULT] Of the 119 cases, FNAC/FCM provided a definite diagnosis of NHL in 89 cases and 15 cases were reported as "highly suggestive of NHL" (sNHL). 11 cases were reported as reactive lymphoid hyperplasia and 4 as lymphocytic thyroiditis. HPE was available in 48/89 cases of NHL, 13/15 of sNHL and 6/11 cases of reactive lymphoid hyperplasia (RLH). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were found as follows: 78.6%, 100%, 100% and 31.5% respectively.

[CONCLUSION] The combination of FNAC-FCM is effective in the cytological diagnosis and classification of NHL and generates reproducible results the majority of the time. However, interpretation of FCM should be performed by a trained cytopathologist only because the graphs ought to be assessed in the light of morphology.