Grading follicular lymphomas in fine-needle aspiration biopsies: the role of ThinPrep slides and flow cytometry.
BACKGROUND
The World Health Organization (WHO) recommends a 3-tier grading system (Grades 1-3) for follicular lymphomas (FLs) based on the absolute number of centroblasts per high-power microscopic field (HPF) in 10 neoplastic follicles. Grades 1 and 2 FL are still managed as indolent FLs, whereas Grade 3 FL is thought to behave more aggressively. In this study, the feasibility of grading FL using ThinPrep (TP) slides and flow cytometry (FC) was evaluated.


METHODS
Fifty-three cases of lymph node fine-needle aspiration (FNA) from patients with histologically confirmed FL (20 Grade 1, 17 Grade 2, and 16 Grade 3) were included. The number of centroblasts present in 300 lymphoid cells and in 10 HPF in TP Papanicolaou-stained slides was evaluated. The percentage of CD10-positive small cells was calculated with FC results. Statistical analysis was performed with the Jonckheer-Terpstra nonparametric trend test and the Wilcoxon rank sum test.


RESULTS
The statistical analysis demonstrated a significant upward trend in the number of centroblasts as the grades increased. Also, all 3 methods had statistically significant results to distinguish different grades of FL, except when FC was used to distinguish Grade 2 from Grade 3 FL.


CONCLUSIONS
Counting centroblasts, either in 300 lymphoid cells or per 10 HPF in TP slides, represented a statistically significant method to separate different grades of FL in FNA samples. Analysis of cell size by FC was not as reliable to distinguish different grades of FL, especially Grade 2 from 3.
Brandao
Guilherme D A
GD
Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Rose
Ruth
R
McKenzie
Susan
S
Maslak
Peter
P
Lin
Oscar
O
D000328:Adult; D000368:Aged; D044963:Biopsy, Fine-Needle; D003584:Cytological Techniques; D005240:Feasibility Studies; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008224:Lymphoma, Follicular / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity