A Proposal for the Performance, Classification, and Reporting of Lymph Node Fine-Needle Aspiration Cytopathology: The Sydney System

Abstract

Background: The evaluation of lymph nodes (LN) by fine-needle aspiration cytology (FNAC) is routinely used in many institutions but it is not uniformly accepted mainly because of the lack of guidelines and a cytopathological diagnostic classification. A committee of cytopathologists has developed a system of performance, classification, and reporting for LN-FNAC. Methods: The committee members prepared a document that has circulated among them five times; the final text has been approved by all the participants. It is based on a review of the international literature and on the expertise of the members. The system integrates clinical and imaging data with cytopathological features and ancillary techniques. The project has received the endorsement and patronage of the International Academy of Cytology and the European Federation of the Cytology Societies. Results: Clinical, imaging, and serological data of lymphadenopathies, indications for LN-FNAC, technical procedures, and ancillary techniques are evaluated with specific recommendations. The reporting system includes two diagnostic levels. The first should provide basic diagnostic information and includes five categories: inadequate/insufficient, benign, atypical lymphoid cells of undetermined/uncertain significance, suspicious, and malignant. For each category, specific recommendations are provided. The second diagnostic level, when achievable, should produce the identification of specific benign or malignant entities and additional information by utilizing ancillary testing. Conclusion: The authors believe that the introduction of this system for performing and reporting LN-FNAC may improve the quality of the procedure, the report, and the communication between cytopathologists and the clinicians. This system may lead to a greater acceptance and utilization of LN-FNAC and to a better interdisciplinary understanding of the results of this procedure.

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

“…LN‐FNA has been used as a diagnostic modality since the early 1950s; however, until recently, there was no well‐established system for its reporting. The Sydney system has been proposed to bring forth uniformity in reporting and to guide management 5,6 . As with any other newly proposed classification system, its validity, reproducibility, and clinical utility need to be ascertained before it can be recommended for routine use.…”

“…The application of ROSE for the reporting of LN cytopathology has also been recommended by the proposed Sydney system. In addition, according to the proposed guidelines, ROSE can reduce the inadequacy as well as the false‐negative rates 5 . We also recommend that cases with predominant necrosis and degenerated cells on the smears should be closely followed up either by a repeat image‐guided FNA from a viable area or an excision biopsy to exclude malignancy.…”

“…According to this system, the cytologic aspirates from lymph nodal masses should be categorized into 5 different diagnostic categories based on the specific cytologic features observed on the smears. These categories include category I/L1: inadequate/nondiagnostic, category II/L2: benign, category III/L3: atypical cells of undetermined significance/atypical lymphoid cells of uncertain significance, category IV/L4: suspicious, and category V/L5: malignant 5,6 …”

Fine needle aspiration in COVID-19 vaccine-associated lymphadenopathy

“…The recently proposed Sydney System for lymph node FNA cytology provides information on how to approach lymphadenopathy to ensure results of the best attainable quality. It provides clear reporting categories with possible differential diagnosis, and recommends further procedures depending on the context of presentation [70]. Detailed clinical information (medical history and physical examination), as well as results from further diagnostic tests such as imaging or serology, are crucial in the evaluation of cytological smears from lymph nodes.…”

Diagnostic Considerations in the Evaluation of Large B-Cells on Lymph Node Cytology Specimens

“…In some institutions, CNB and FNA have become primary diagnostic procedures in patients with suspected lymphoma due to the less-invasive nature, ease of scheduling, and overall lower cost per procedure. Recently, an international committee of cytopathologists proposed guidelines for standardizing the evaluation of lymph nodes by FNA cytopathology [1]. Prior studies have shown that FNA in conjunction with CNB help categorize lymph node specimens with actionable diagnoses in 67–100% of cases, allowing initiation of treatment or a definitive determination of benign etiology that requires no further intervention [2, 3].…”