The accuracy of combined cytopathologic and flow cytometric analysis of fine-needle aspirates of lymph nodes.

We studied flow cytometry in 156 fine-needle aspirations (FNAs) of lymph nodes performed between June 1993 and September 1998. Information from flow cytometry was combined with cytomorphologic evaluation, and the diagnosis determined by using combined modalities was compared with tissue biopsy results or clinical follow-up. In 74 cases, a combined cytopathologic-flow cytometric diagnosis of lymphoma was made; histologic material was available for 52 patients; in no case was a benign process found. The lymphoma grade assigned agreed with histopathologic findings in 45 of 48 cases with a specific cytologic diagnosis. Treatment was initiated on the basis of the FNA alone for 17 of 52 patients with a history of lymphoma and in 22 additional patients with no follow-up biopsy. Among 71 cases in which the diagnosis using both modalities was benign, the only false-negative was 1 case of Hodgkin disease. Of the 156 cases, 11 were considered atypical or suggestive of lymphoma; biopsies from 8 of 10 patients revealed lymphoma. A combination of flow cytometry and cytomorphology of cells obtained by FNA of lymph nodes can distinguish between benign and malignant lymphoid infiltrates and support a diagnosis of lymphoma that permits definitive therapy in most cases.