Assessment of risk of malignancy by application of the proposed Sydney system for classification and reporting lymph node cytopathology

Abstract

BACKGROUND Fine‐needle aspiration cytology (FNAC) is one of the most commonly used techniques for evaluating lymphadenopathy. Recently, the Sydney system was proposed for assessing the performance, classification, and reporting of lymph node (LN) cytopathology. The present study was conducted to assess the risk of malignancy associated with each of the diagnostic categories of the proposed Sydney system. METHODS This was a 2‐year retrospective study of LN‐FNAs; cytologic diagnoses were categorized by the proposed Sydney system. Cytological diagnoses were correlated with the corresponding histopathological diagnoses to assess diagnostic accuracy and risk of malignancy for each diagnostic category. RESULTS Of 23,335 FNAs during the study period, 6983 (30%) were performed on LNs. Of these, 289 (4.1%) cases were reported as nondiagnostic/inadequate (L1); 3397 (48.6%) were reported as benign (L2); 33(0.5%) as atypical cells of undetermined significance (L3), 96 (1.4%) as suspicious for malignancy (L4) and 3168 (45.4%) as malignant (L5). Subsequent histopathology was available for 618 (8.8%) cases. On cytohistopathologic correlation, 552 (89.3%) were concordant and 66 (10.7%) discordant. The overall sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of LN‐FNA were 79.9%, 98.7%, 98.4%, 83.1%, and 89.3%, respectively. The risk of malignancy was 27.5% for the nondiagnostic category, 11.5% for the benign, 66.7% for the atypical, 88% for the suspicious, and 99.6% for the malignant categories. CONCLUSIONS FNAC has high diagnostic accuracy for the diagnosis of various LN pathologies. Application of the proposed Sydney system can help in achieving uniformity and reproducibility in cytologic diagnoses and also help in risk‐stratification on cytology.

Accuracy of fine‐needle aspiration of lymph nodes: A cancer center’s experience

“…Our series showed very high specificity and PPV, in accordance with previous studies 4,5,9,11,12 . We had only one FP case, consisting of a lymph node suspicious for papillary thyroid carcinoma metastasis.…”

Ultrasound-Guided Fine-Needle Aspiration of Superficial Lymphadenopathy Performed by Interventional Pathologists: The Applicability of the Sydney System from 2 Years of Experience and 363 Cases

“…From our experience, we believe that this low-rate of insufficient samples is due to several factors: the superficial location of the lymphadenopathies (which makes them relatively easier to access), the expertise of the interventional pathologist performing USFNA, and the real-time decision-making associated with ROSE and sample management. As expected, more than half of the lymphadenopathies corresponded to the benign category, in line with other studies [11,35]. All cases of atypia of uncertain significance were classified in the subcategory atypical lymphoid cells of uncertain significance, similar to the majority of cases in the suspicious category, in which 19 of 21 specimens were suggestive of a lymphoproliferative process.…”

“…Reclassifying our system into the Sydney system categories revealed that the rate of samples with inadequate/ insufficient results was <4%, 1 of the lowest reported to date [3,34]. This is in agreement with 1 of the few articles published that addresses the applicability of the Sydney system [35]. From our experience, we believe that this low-rate of insufficient samples is due to several factors: the superficial location of the lymphadenopathies (which makes them relatively easier to access), the expertise of the interventional pathologist performing USFNA, and the real-time decision-making associated with ROSE and sample management.…”

A Novel Approach to Classification and Reporting of Lymph Node Fine-Needle Cytology: Application of the Proposed Sydney System

“…As expected, the L2 category showed the lowest ROM (1.92%). Notably, in our series, few infective lymphadenopaties were present; however, the utility of FNC as a noninvasive procedure in this setting in most parts of the world cannot be overemphasized [26]. Interestingly, the two FN diagnoses were represented by subcapsular breast metastases in axillary lymph nodes, highlighting that partial lymph nodal involvement must be considered as a possible cause of misclassification (Figure 1).…”

“…To fulfil the latter requirement, in 2020, an expert panel published the proposal of the Sydney system for performing classification and reporting of lymph node cytopathology, introducing the use of five diagnostic categories [25]; moreover, taking into account the wide spectrum of lymph node pathologies, a second diagnostic level, aimed at the identification of specific diagnostic entities, has been proposed. However, the Sydney system is still underutilized and to date there are limited data in the literature [26]. To fill this knowledge gap, the aim of the present study was to evaluate the applicability of the Sydney system to lymph node FNC and to assess the diagnostic accuracy and the risk of malignancy (ROM) for each diagnostic category.…”