Fine needle aspiration cytology in the evaluation of lymphoid lesions: a retrospective study of the utility of flow cytometry in conjunction with morphology

BACKGROUND AND OBJECTIVE: Fine needle aspiration (FNA) cytology, in conjunction with flow cytometry, is now widely used as a reliable and accurate method for the assessment of various lymphoid lesions, especially for lesions situated in odd locations where obtaining biopsy and monitoring for recurrence in previously diagnosed cases of lymphoma are difficult. The objective of this study was to determine the utility of FNA and immunophenotyping in the assessment of lymphoid lesions, and to find whether flow cytometry is more useful in the evaluation and subclassification of the small cell morphology group of lymphomas than in the large cell morphology group of lymphomas. DESIGN AND SETTING: Retrospective analysis of patients diagnosed with lymphoma over at a 5-year period. PATIENTS AND METHODS: All 175 FNA cases were followed carefully either clinically or histologically for at least 5 years. We compared the utility of flow cytometry in the diagnosis of small cell morphology lymphomas to large cell morphology lymphomas. RESULTS: Flow cytometry was performed on 72 of 175 (41%) of FNA specimens clinically suspicious of lymphoma. The excisional follow-up biopsy was obtained in 78 of 175 (44.5%) cases. Based on cytomorphologic evaluation, 82 cases (47%) were considered negative, 34 cases (19%) were considered atypical, 32 cases (18%) were positive for NHL-small cell morphology, 21 cases (12%) were positive for non-Hodgkin lymphoma (NHL)-large cell morphology, 3 cases (2%) were positive for NHL, and 3 cases (2%) were nondiagnostic. Immunophenotyping utilizing flow cytometry was the diagnostic parameter in 28 of 32 cases (88%) of the NHL-small cell morphology group and in 11 of 24 cases (46%) of the NHL-large cell morphology/Hodgkin lymphoma group. CONCLUSIONS: Immunophenotyping by flow cytometry is more essential for the accurate evaluation and classification of small cell morphology than large cell morphology lymphoid lesions in FNA cytology.