Fine-needle aspiration biopsy in the diagnosis and classification of primary and recurrent lymphoma: A retrospective analysis of the utility of cytomorphology and flow cytometry

We retrospectively reviewed our experience with the fine-needle aspiration biopsy (FNAB) diagnosis of primary and recurrent lymphoma to assess the abi lity of cytomorphology with and without ancillary now cytometry (PCM) analy sis to diagnose and subclassify these tumors according to the Revised Europ ean-American Lymphoma/World Health Organization classifications. We reviewe d 139 consecutive FNABS of 84 primary and 55 recurrent lymphomas. FCM was s uccessful in 105 (75%) cases. The overall results, including cases without FCM, included 93/139 (67%) true positive, 7 (5%) false negative, and 39 ind eterminate (27 [19%] suspicious and 12 [9%] atypical) diagnoses of lymphoma In cases with FCM, there were 80/105 (77%) true positive, no false negativ e, and 25 indeterminate diagnoses (15 [14%] suspicious and 10 [9%] atypical ). The overall results of the 84 primary lymphomas were 55 (67%) true posit ive, 5 (5%) false negative, and 24 indeterminate (14[16%] suspicious and 10 [12%] atypical) diagnoses for lymphoma Of the 68 primary lymphomas analyze d with FCM, 50 [74%] were true positives, and 28 were indeterminate (11 [16 %] suspicious and 7 [10%] atypical). There were no false negatives. Diagnos tic accuracy varied among lymphoma subtypes. Subclassification of the posit ive cases were initially conclusive in only 55/93 cases (59%). However, a r etrospective review of the morphologic together with FCM data in 15 of the 23 unclassified cases improved the overall subclassification of positive ca ses to 77%. Subclassification was best in small lymphocytic lymphoma/chroni c lymphocytic leukemia, lymphoplasmacytic lymphoma, Burkitt's lymphoma, man tle cell lymphoma, and plasmacytoma (all 100%). Subclassification was poor in marginal-zone lymphoma (33%), and initially as well in diffuse large B-c ell lymphoma (62%), but it improved on review (95%), as did subclassificati on of follicular lymphoma (77 to 100% on review). Hodgkin's disease was rec ognized as malignant in only 44% of the cases (7/16) and was classified as such based on morphology alone. This review of our early efforts to diagnos e and subclassify lymphoma with FNAB and FCM indicates that although a diag nosis and proper subclassification of lymphoma can be made with certainty i n the majority of cases, recurrent or primary, it requires close coordinati on of cytomorphology and immunophenotyping data, which often comes with clo se cooperation of cytopathologists and hematopathologists. A mere cytologic al diagnosis of positive for lymphoma is no longer acceptable if FNAB is to become an independent diagnostic tool for lymphoma.