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

Abstract

Fine-needle cytology (FNC) is a useful diagnostic tool in the first line evaluation of lymphadenopathy of unknown aetiology. Nevertheless, considering the large number of conditions presenting as lymphadenopathy, lymph node cytology represents a challenging scenario. Recently, an expert panel published the proposal of the Sydney system for performing classification and reporting of lymph node cytopathology; the aim of the present study was to evaluate the applicability of this system. Thus, 300 lymph node FNCs performed over 1 year were reviewed and categorized according to the Sydney system classification. Overall, n = 20 cases (6.7%) were categorized as L1-inadequate/non-diagnostic; n = 104 (34.7%) as benign (L2); n = 25 (8.3%) as atypical (L3); n = 13 (4.3%) as suspicious (L4), and n = 138 (46%) as malignant (L5). FNC diagnoses were correlated with histopathologic and clinical follow-up to assess the diagnostic accuracy and the risk of malignancy (ROM) for each diagnostic category. Statistical analysis showed the following results: sensitivity 98.47%, specificity 95.33%, positive predictive value 96.27%, negative predictive value 98.08%, and accuracy 97.06%. The ROM was 50% for the category L1, 1.92% for L2, 58.3% for L3, and 100% for L4 and L5. In conclusion, FNC coupled with ancillary techniques ensures satisfactory diagnostic accuracy and the implementation of the Sydney system may improve the practice of cytopathologists.

Diagnostic accuracy of Thinprep® in cervical lymph node aspiration: Assessment according to the Sydney system

“…In other organ‐specific diagnostic systems, the lowest ROM values in the benign category and the highest in the malignant category were reported, and as expected, the ROM was calculated as 0.7% in L2 and 100% in L5, which is consistent with the literature 19,23 …”

“…As expected, the ROM values of the L4 and L5 categories were calculated to be 100%. These data are similar to other organ‐specific cytology diagnostic systems and studies using the Sydney system in the literature 19,23 …”

“…Therefore, it is recommended that ROSE of lymph node cytology should also be reported according to the Sydney system, and necrosis or degenerated cell‐rich samples should be closely followed up clinically or continued sequentially by FNAC repetition, core needle biopsy, excision biopsy to avoid the possibility of malignancy 17,19 . In the absence of experienced technicians or technical facilities for ROSE, it is reported that conventional smear utilizing institutions should consider the use of liquid‐based cytology 23 . It was previously reported that LBC has high diagnostic accuracy in lymph node FNAC and is superior to conventional smear 24–34 …”

“…Partial effacement of one lymph node was determined as the reason for oversight of follicular lymphoma, and previous studies have reported that these cases may be mistakenly diagnosed as reactive lymphoid hyperplasia due to the florid reactive cells aspirated from the non‐involved part of the lymph node 23,31,45–51 . In addition, the lack or scantiness of a typical Reed‐Sternberg and misinterpretation of lacunar cells on a reactive polymorphic background might lead to misdiagnosis of Hodgkin lymphoma in cytology smears.…”

“…As four samples in this work, it was stated that the diagnosis of L3‐ALUS was made based on the presence of large cells with mild irregular nuclei, prominent nucleoli, and cytoplasm. These cells are thought to be immunoblasts or centroblasts 23 …”