Fine-needle cytology and flow cytometry immunophenotyping and subclassification of non-Hodgkin lymphoma: a critical review of 307 cases with technical suggestions

Flow cytometry (FC) is a useful adjunct to fine-needle aspiration cytology (FNC) in evaluating lymphoproliferative disorders. The authors present a critical review of 307 lymph nodal and extra lymph nodal lymphoproliferative disorders that were diagnosed with FNC and FC. METHODS: FC was performed over a 4-year period on 185 palpable and 122 impalpable lymph nodal and extra lymph nodal lymphoproliferative processes under ultrasound or computed tomography guidance. FC was performed using the following fluoresceinated antibodies: CD3, CD4/CD8, CD2/CD7/CD3, CD5/CD10/CD19, CD19/kappa/lambda, FMC7/CD23/CD19, CD38/CD56/CD19, and bcl-2. The series included 15 inadequate, 10 suspicious, and 135 benign reactive hyperplasias (BRHs); 70 primary non-Hodgkin lymphomas (NHLs), and 77 recurrent NHLs (rNHLs). FC/FNC diagnoses of suspicious, NHL, and rNHL were controlled either histologically or clinically or by the interphase fluorescence in situ hybridization demonstration of t(11;14)(q13;q32) in two cases of mantle cell lymphoma. BRHs were controlled by follow-up. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the FC/FNC diagnoses of NHL, rNHL, and BRH were calculated as well as the identification of specific subtypes among the small- and medium-sized cells. RESULTS: Statistical analysis showed 93% sensitivity, 100% specificity, 100% PPV, and 91% NPV in NHL, rNHL, and BRH discrimination. The subclassification of small cell and medium-sized NHLs showed 63% sensitivity, 88% specificity, 95% PPV, and 37% NPV. CONCLUSIONS: FC applied to FNC enhanced the precision of cytologic diagnosis in lymph nodal and extra lymph nodal lymphoproliferative disorders and allowed further subclassification in more than half of the cases, thus avoiding invasive surgical biopsies in many patients