Diagnostic value of lymph node fine-needle aspiration cytology

This study aims to assess the diagnostic accuracy of cytology by comparing the results of fine-needle aspiration cytology (FNAC) and histopathologic examination.

A 4-year retrospective study design was conducted on FNAC samples from the lymph nodes of patients in our hospital between January 2015 and December 2018. The cytopathological diagnoses were compared with the histopathological results of the same excised lymph nodes. Diagnostic sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy rate were calculated.

A total of 392 lymph nodes were aspirated during the study period. Cytologic analysis of the lymph nodes revealed the following: Reactive lymphoid hyperplasia, 239 (61%); metastatic, 61 (15.6%); granulomatous lymphadenitis, 24 (6.1%); suspicious, 24 (6.1%); pyogenic abscess, 10 (2.6%); necrosis, 4 (1%); non-Hodgkin lymphoma, 2 (0.5%); and non-diagnostic, 28 (7.1%). Immunohistochemical analysis was performed on 26 (6.6%) cases to the cell block samples. Histopathological correlation was available in 73 (18.7%) cases. The overall diagnostic sensitivity, specificity, PPV, and NPV of FNAC of lymph nodes were 87.9%, 100%, 100%, and 89.7%, respectively. The overall diagnostic accuracy was 94.1%. In case of malignancies, the histopathological correlation was 100%. Of four cases with false negative, three were low-grade non-Hodgkin lymphoma and one was granulocytic sarcoma.

FNAC of lymph nodes is a safe, easy, cheap, quick diagnostic tool and reduces the need for diagnostic excisional biopsy in many patients. Cytological diagnosis can be supported with immunohistochemical analysis of cell block samples. However, lymphomas, particularly low-grade non-Hodgkin lymphomas, are a diagnostic challenge and additional studies such as flow cytometry are required in cases with suspicious for lymphoma.