[363] Grading Follicular Lymphomas/Diffuse Large B Cell Lymphoma by Fine-Needle Aspiration Cytomorphology and Flow Cytometry

Y Chen, DM Dorfman, ES Cibas, TJ Wieczorek. Harvard Medical School and Brigham and Women's Hospital, Boston, MA; Faulkner Hospital, Boston, MA

Background: Fine-needle aspiration (FNA) is useful for the diagnosis and classification of lymphoproliferative disorders. The diagnosis of follicular lymphoma (FL) and its distinction from diffuse large B cell lymphoma (DLBCL), however, require grading the neoplasm for optimal clinical management. There is no widely accepted means of grading based on FNA sampling alone, although a cutoff of >40% large cells has been suggested for classification as DLBCL. The purpose of this study was to determine if accurate grading of FL/DLBCL can be accomplished by cytomorphology or flow cytometry (FC).
Design: We studied the cytomorphology and flow cytometry data derived from 29 FNA specimens and the histology and flow cytometry data for 63 histologic specimens of FL/DLBCL; an additional 28 histologic specimens were studied as follow-up to the FNAs. A grade was assigned to the histologic samples by consensus according to the WHO scheme; WHO grades were then lumped into two clinically significant grades: low grade (WHO grades 1 and 2) and high grade (WHO grade 3 and DLBCL). For each FNA sample, we quantified the percentage of large cells by cytomorphology, assigning the specimen high grade if large cells comprised >40% of the cellularity. For all the lymphoma samples, we calculated the mean forward scatter and side scatter for the neoplastic cells by FC and attempted to establish cutoffs corresponding to histologic grade.
Results: Concordance on the grade assigned to the FNA sample and follow-up histologic specimen was 79% (23/29). For the FC cutoffs chosen (forward scatter > 1.2 or side scatter > 2.0, both normalized with accompanying T cells as an internal standard), the concordance between the grade assigned by FC and histology was 78% (72/92). The concordance on histologic grade among 3 pathologists (2 reviewers and the original pathologist who interpreted the biopsy) was 85% (77/91).
Conclusions: FL/DLBCL can be graded with good reliability by an evaluation of the percentage of large cells on FNA samples and by simple cutoffs based on forward/side scatter as determined by FC.
Category: Cytopathology

Wednesday, March 11, 2009 1:00 PM

Poster Session VI # 49, Wednesday Afternoon