Lymph node cytology: a follow-up audit of 456 cases in a tertiary healthcare institution

Abstract

Objectives This retrospective audit aims to evaluate the diagnostic performance of fine needle aspiration (FNA) in assessing superficial lymphadenopathy in a tertiary healthcare institution. Methods We analysed all superficial lymph node FNAs reported in 2011 in the National University Hospital, Singapore. On-site provisional reports and adequacy assessment were available for selected cases. Alcohol-fixed and air-dried smears were prepared for each case. Cell blocks, immunoperoxidase and/or histochemical studies were performed when required. FNA diagnoses were correlated with final histological diagnoses. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were calculated for cases with definite histological diagnosis. Results There were 456 cases, classified into benign [n = 273 (59.8%)], malignant [n = 112 (24.5%), including 96 (85.7%) metastatic carcinoma and 16 (14.2%) lymphoma], atypical [n = 14 (3.1%)] and non-diagnostic [n = 57 (12.5%)]. Histological follow-up was available in 66 cases. For malignant diagnoses, sensitivity was 80.65%, specificity 96.43%, PPV 96.15% and NPV 81.82%. Sensitivity for metastases and lymphoma were 93.75% and 66.67% respectively. Agreement between provisional and final diagnoses was 90.2%; and between on-site adequacy assessment and final adequacy was 96.44%. Conclusion Lymph node FNA is a safe, cost effective and accurate first line diagnostic modality, with high diagnostic specificity and PPV.