title: Grading of follicular lymphoma in cytological samples.
abstract: OBJECTIVE
  The treatment of follicular lymphoma (FL) depends on its grade. The current World Health Organization (WHO) 2008 Classification of Tumours of Haematopoietic and Lymphoid Tissues recommends the grading of FL on histological samples according to the Mann and Berard method, taking into consideration the number of centroblasts. There is no generally accepted method for the grading of FL in fine needle aspiration biopsy (FNAB) samples. The aim of the present study was to devise a grading system for FL in cytological samples.
  
  
  METHODS
  Flow cytometry (FC) was performed on 60 FNAB samples of patients with primary FL. We assumed that FL cells larger than reactive T lymphocytes on FC histograms corresponded to centroblasts. The percentage of large cells was calculated and compared with histological grade, proliferative activity and number of centroblasts per high-power field (HPF) on histological slides, and with survival.
  
  
  RESULTS
  The histological analysis of lymph nodes revealed 20 patients with high-grade and 40 patients with low-grade FL. The percentage of large cells in FNAB samples correlated significantly with histological grade (P = 0.02), MIB1 status (P < 0.001) and the number of centroblasts per HPF (P < 0.001). An age over 60 years and a percentage of large cells over 50% in FNAB samples were found to have a statistically significant impact on survival by univariate analysis (P = 0.001 and P = 0.006, respectively).
  
  
  CONCLUSIONS
  The percentage of large lymphoma cells in FNAB samples of FL determined by FC can be used as a reliable method for FL grading, as it is comparable with the histological grading system.
authors: Department of Cytopathology, Institute of Oncology, Ljubljana, Slovenia.
authors: U
authors: U
authors: Klopčič
authors: Department of Cytopathology, Institute of Oncology, Ljubljana, Slovenia.
authors: J
authors: J
authors: Lavrenčak
authors: Department of Pathology of the , Institute of Oncology Ljubljana, Slovenia , Ljubljana.
authors: G
authors: G
authors: Gašljević
authors: Department of Pathology, University Clinical Center Ljubljana, Zaloška cesta 2, Ljubljana, Slovenia.
authors: M
authors: M
authors: Bračko
authors: Department of Cytopathology, Institute of Oncology, Ljubljana, Slovenia.
authors: Ž
authors: Ž
authors: Pohar-Marinšek
authors: Department of Cytopathology, Institute of Oncology, Ljubljana, Slovenia.
authors: V
authors: V
authors: Kloboves-Prevodnik
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle; D003581:Cytodiagnosis; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008224:Lymphoma, Follicular / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading
keywords: fine needle aspiration biopsy; flow cytometry; follicular lymphoma; grading; percentage of large lymphoma cells; survival