Lymphoid cell aggregates: A useful clue in the fine‐needle aspiration diagnosis of follicular lymphomas

Abstract

Among the various types of lymphoma, follicular lymphoma (FL) is known to have significant limitations in cytologic diagnosis by the fine-needle aspiration (FNA) method. The diagnostic accuracy (DA) for non-Hodgkin's lymphoma (NHL) by FNA was evaluated by review of 82 cases of histologically proved NHL after prior FNA. The DA for all NHLs was 66% (54/82), and that for low-grade lymphomas, including small lymphocytic lymphoma, follicular small-cleaved cell lymphoma, and follicular mixed cell lymphoma, was 71% (12/17). The DA for FL was 69% (11/16). Review of individual surgical and cytologic materials from FLs revealed a tendency to show fibrosis in the cytologically false-negative group and diffuse areas of lymphoma in the true-positive group. The presence of “aggregation” of uniform lymphoid cells, probably due to cell adhesions with the support of dendritic reticulum cells, was seen in 55% of true-positive FL (6/11). In contrast, only 28% of true-positive diffuse large cell lymphomas (5/18) showed a mild degree of aggregation, and none of 7 cases of true-positive diffuse small-cleaved cell lymphoma showed this feature. The aggregation of cells was not pathognomonic of FL, but its presence with a homogeneous cellular constituent and the paucity of tingible-body macrophages helped us to predict FL. Also, it was a feature distinguishing FL from diffuse small-cleaved cell lymphoma (P = 0.025). Diagn. Cytopathol. 1997;17:467–471. © 1997 Wiley-Liss, Inc.