The Application of the Proposed Sydney System for Reporting Lymph Node Cytopathology: A Five-Year Experience of an Academic Institution in South India

Abstract

Introduction: Fine needle aspiration biopsy (FNAB) is a routinely used investigation in the evaluation of lymph node pathologies. However, there exists a lack of uniformity in cytopathology reporting owing to the non-availability of standard guidelines. Recently, a novel system for reporting lymph node cytopathology has been proposed. The present study aimed to analyze the utility of the proposed system in cytopathology reporting in our institution. Materials: FNAB of lymph nodes performed over a period of 5 years were categorized as per the proposed Sydney system. The diagnoses on cytopathology were correlated with histopathologic diagnoses to assess the diagnostic accuracy. The rate of malignancy (ROM) for each category was calculated. Results: A total of 747 lymph node FNABs were included in the study. Histopathology was available in 262 cases. ROM in categories I-V was 26.3%, 7.2%, 76.9%, 82.3%, and 100.0%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of FNAB when considering category L3 to represent benign cytopathology were 84.2%, 97.5%, 97.1%, and 86.2%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of FNAB when considering category L3 to represent malignant cytopathology were 92.56%, 95.08%, 94.9%, and 92.8% respectively. Conclusion: The study substantiates the usefulness of the proposed Sydney system in lymph node cytopathology in enhancing better communication between clinicians and cytopathologists. The use of ancillary techniques like immunocytochemistry and flow cytometry will aid in arriving at a more precise diagnosis.

Uses and limitations of small‐volume biopsies for the diagnosis of lymphoma

“…This system has been applied in multiple studies involving academic medical centers throughout the world and has generally demonstrated favourable results, with an expected increasing risk of malignancy (ROM) among the first diagnostic level categories ranging from 0.7% to 11.5% for benign, 82.3%–100% for suspicious and 95%–100% for malignant. ROM for the atypical and insufficient/non‐diagnostic category show an expected degree of considerable variability across studies, ranging from 28.6%–88.8% for atypical diagnoses and 16.6%–66.7% for insufficient/non‐diagnostic specimens 10–13,31–33 . Performance characteristics have also generally been high ranging from 79.9% to 98.97% for sensitivity, 85.53%–98.7% for specificity, 69.44%–98.4% for PPV, 83.1%–99.58% for NPV and 84.51%–98.75% for accuracy 10–13,31,33 .…”

“…ROM for the atypical and insufficient/non‐diagnostic category show an expected degree of considerable variability across studies, ranging from 28.6%–88.8% for atypical diagnoses and 16.6%–66.7% for insufficient/non‐diagnostic specimens 10–13,31–33 . Performance characteristics have also generally been high ranging from 79.9% to 98.97% for sensitivity, 85.53%–98.7% for specificity, 69.44%–98.4% for PPV, 83.1%–99.58% for NPV and 84.51%–98.75% for accuracy 10–13,31,33 . Caputo et al.…”

“…Although FNA performance utilizing the Sydney System is overall high in cases of lymphadenopathy of unknown origin, it is important to note that some studies have demonstrated that missed lymphoma appears to comprise a large proportion of discordant cases. Among three large studies, the majority of false negatives represented FNA samples diagnosed as benign with subsequent biopsy demonstrating lymphoma (34/35, 11 5/6 33 and 6/9 12 ). In general, false positives were very rare across studies; however, among four studies, nearly all false positives represented an over‐diagnosis of lymphoma (4/4, 11 1/1, 33 2/3, 12 2/2, 10 ).…”

“…Among three large studies, the majority of false negatives represented FNA samples diagnosed as benign with subsequent biopsy demonstrating lymphoma (34/35, 11 5/6 33 and 6/9 12 ). In general, false positives were very rare across studies; however, among four studies, nearly all false positives represented an over‐diagnosis of lymphoma (4/4, 11 1/1, 33 2/3, 12 2/2, 10 ). These findings further highlight that if clinical characteristics do not align with the FNA diagnosis, additional sampling should be pursued.…”

“…Additionally, small biopsies may not provide sufficient tissue for extensive ancillary studies and are more prone to poor quality due to necrosis, crush artefact or haemorrhage especially if the lesion is sclerotic 8 . False negatives and false positives have been reported on small biopsies, which can lead to incorrect diagnoses and treatment 9–13 . The College of American Pathologists (CAP) and American Society for Clinical Pathology (ASCP) advise against FNA in the primary diagnosis of lymphoma and suggest that a SB or CNB be obtained 14 .…”