Real‐world experience with the Sydney System on 1458 cases of lymph node fine needle aspiration cytology

Abstract

Introduction Lymph node (LN) fine needle aspiration cytology (FNAC) is a safe, quick, inexpensive, reliable, and minimally invasive technique for the diagnosis of lymphadenopathies. Recently, an international committee of experts proposed guidelines for the performance, classification, and reporting of LN‐FNAC: the Sydney System. We set out to analyse the diagnostic performance of the Sydney System in a retrospective study. Methods We retrieved 1458 LN‐FNACs, reformulated the diagnoses according to the Sydney System, and compared them to the histological control where available (n = 551, 37.8%). Results The risk of malignancy for each of the five categories was 66.7% for inadequate/insufficient, 9.38% for benign (overall: 0.84%), 28.6% for atypical, 100% for suspicious and 99.8% for malignant. LN‐FNAC showed a sensitivity of 97.94%, a specificity of 96.92%, a positive predictive value of 99.58%, and a negative predictive value of 86.30%. Conclusions These data support the usage of LN‐FNAC as an agile first‐level technique in the diagnosis of lymphadenopathies. The Sydney System supports and enhances this role of LN‐FNAC, and its adoption is encouraged. In negative cases, coupled with ancillary techniques, LN‐FNAC can reassure the clinician regarding the benignity of a lymphadenopathy and indicate the need for clinical follow‐up, which will catch possible false negatives. In positive cases, LN‐FNAC can provide sufficient information, including predictive biomarkers, to initiate management and obviate the need for subsequent, more invasive procedures. Given its speed, minimal invasiveness, and low cost, LN‐FNAC can be performed in most cases, even when more invasive techniques are not feasible.

Observations on hematogones with light chain restriction.

“…Checking on the literature we found similar cases showing LCR with or without CD10 positivity, without IGH gene rearrangement or t(14;18), described in different organs and different samples [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] . The common aspect of this heterogeneous group of cases was the clinical data, in almost all the corresponding patients, of immunodepression, as is the case in the series of El Husssain et al [1] , or autoimmune diseases [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] . These clones, at FC analysis and, mainly in extra-nodal sites, did not seem to exceed 20% of the gated B-cells.…”

“…The case was considered a relapse of FL but the histological control revealed a florid follicular hyperplasia [3] . We also recently described one false-positive cytological diagnosis due to LCR that turned out to be a case of progressively transformed germinal centers without IGH rearrangement at histology [4] . Checking on the literature we found similar cases showing LCR with or without CD10 positivity, without IGH gene rearrangement or t(14;18), described in different organs and different samples [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] .…”

“…We also recently described one false-positive cytological diagnosis due to LCR that turned out to be a case of progressively transformed germinal centers without IGH rearrangement at histology [4] . Checking on the literature we found similar cases showing LCR with or without CD10 positivity, without IGH gene rearrangement or t(14;18), described in different organs and different samples [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] . The common aspect of this heterogeneous group of cases was the clinical data, in almost all the corresponding patients, of immunodepression, as is the case in the series of El Husssain et al [1] , or autoimmune diseases [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] .…”

“…Therefore, we called them “microclones” [5] and supposed that, in cases in which there is an impairment of the immune system either for autoimmune stimulation, or for a compensation for defective T-cell response, small clones of monotypic B-cell may produce LCR. The possible occurrence of LCR in non-lymphomatous processes has been one of the reasons for which a recent proposal for the performance, classification, and reporting of lymph node fine-needle aspiration cytopathology (the Sydney system) [ 4 , 10 ] adopted the criteria proposed for clonality assessment of lymphomas by the EuroClonality/BIOMED-2 guidelines [11] , but recommends also to utilize, in case of LCR in lymph node FNAC, additional morphological, phenotypical or molecular criteria for the diagnosis of lymphoma on cytological samples.…”

Cytological Diagnosis of Aggressive Small-Cell Lymphomas

“…Intracellular markers, both cytoplasmic and nuclear, which historically constituted one of the main limits of FC, have also recently become measurable [32]. In general, FC is extremely useful in aspirates consisting predominantly of small-medium lymphocytes, where morphology alone cannot reliably distinguish benign from low-grade malignant [11, 15, 33, 34].…”