Combined applications of fine needle aspiration cytology and Flow cytometric immunphenotyping for diagnosis and classification of non Hodgkin Lymphoma

AIMS AND OBJECTIVES: In this present study we have evaluated the feasibility of sub-classification of non-Hodgkin's lymphoma (NHL) cases according to World Health Organization's (WHO) classification on fine needle aspiration cytology (FNAC) material along with flow cytometric immunotyping (FCI) as an adjunct. MATERIALS AND METHODS: In this five years study, only cases suggested or confirmed as NHL by FNAC were selected and FCI was performed with a complete panel of antibodies (CD3, CD2, CD 4, CD5, CD8, CD7, CD10, CD19, CD20, CD23, CD45, κ and λ) by dual color flow cytometry. Both cytologic findings and FCI data were interpreted together to diagnose and sub-classify NHL according to WHO classification. Wherever possible the diagnoses were compared with cytology. RESULTS: There were total 48 cases included in this study. The cases were classified on FNAC as predominant small cells (12), mixed small and large cells (5) and large cells (26). In five cases a suggestion of NHL was offered on FNAC material and these cases were labeled as NHL not otherwise specified (NHL-NOS). Flow cytometry could be performed in 45 cases (93.8%) and in rest of the three cases the material was inadequate because of scanty blood mixed aspirate. Light chain restriction was demonstrated in 30 cases out of 40 cases of B-NHL (75%). There were 15 cases each of κ and λ light chain restriction in these 30 cases. With the help of combined FCI and FNAC, it was possible to sub-classify 38 cases of NHL (79%) according to WHO classification. Combined FNAC and FCI data helped to diagnose 9 cases of small lymphocytic lymphoma (SLL), 2 cases of mantle cell lymphoma (MCL), 4 cases of follicular lymphoma (FL), 17 cases of diffuse large B lymphoma (DLBL) and 6 cases of lymphoblastic lymphoma. Histopathology diagnosis was available in 31 cases of NHL out of which there were 14 recurrent and 17 cases of primary NHL. Out of 15 DLBL cases diagnosed on FCI and FNAC, histology confirmed 14 cases and one of these cases was diagnosed as Burkitt's lymphoma on histology. Cases of FL (4), SLL (3) and MCL (2) were well correlated with histopathology. Out of the five cases suggestive of NHL on cytology, histopathology was available in four cases. Histology diagnosis was given as DLBL (1), SLL (1), anaplastic large cell lymphoma (1) and FL transformed into large cell NHL (1). Considering histopathology as gold standard, diagnostic specificity of combined FNAC and FCI was 100% (31/31) and sensitivity in sub-classification was 83.8% (26/31). CONCLUSION: FNAC combined with FCI may be helpful in accurately sub-classifying NHL according to WHO classification. Many of the subtypes of NHL such as FL and MCL which were previously recognized as a pure morphologic entity can be diagnosed by combined use of FNAC and FCI. Other ancillary investigations such as chromosomal changes, cell proliferation markers etc. may be helpful in this aspect.