Flow cytometry in reactive lymph node aspirates: Evaluation of distribution of populations with immunophenotypic
Priyanka Goel1, Seema Acharya1, Sana Ahuja1
1Department of Pathology, Shri Guru Ram Rai Institute of Medical and Health Sciences, Dehradun, India.
Background:
Diagnostic accuracy of fine needle aspiration cytology for lymphomas has markedly improved when used in conjunction with flow cytometry (FCM), especially to differentiate reactive lymph node aspirates from low-grade lymphomas, a challenge for cytopathologists. Lymphoma diagnosis by FCM depends on detection of immunophenotypic B- and T-cell outliers, also present in benign lymph nodes albeit in subsets of cells. These can mimic heterogenous populations obtained from lymphomas partially involving lymph nodes.
Methods:
In the present study, FCM of fine needle aspiration/scrape material from 30 cases of benign lymph nodes was evaluated for the distribution of lymphoid populations and the presence and percentages of immunophenotypic outliers.
Results:
The majority of the samples were cervical nodes with all cases showing T-cell predominance. CD5/CD19 co-expression was seen in 23.94 ± 9.51% (20 cases) and CD10/CD19 co-expression in 3.2%-20.2% (8 cases) of B-cell events. None of these cases showed light chain restriction. Loss of CD7 (2%-28.4%) and CD5 (12.7%) expression was seen in 17 cases and 1 case, respectively, of T-cell events.
Conclusion:
Immunophenotypic outliers suggestive of lymphomas could be seen in non-lymphomatous lymph node aspirates in a subset of the cell population. However, they could be defined as benign due to absence of light chain restriction and normal CD4:CD8 ratios in all but one case, which was confirmed to be benign after clinical correlation and excisional biopsy. Thus, multiparameter FCM along with clinicoradiological correlation can prevent overdiagnosis of lymphomas.
