ABSTRACT
The accuracy of fine needle aspiration cytology (FNAC) of the lymph node was investigated through a review of 176 FNAC cases and the corresponding biopsies. We chose 157 FNAC cases after the exclusion of 19 inadequate ones. Sensitivity of malignancy was 94.0%, specificity 100%, false negativity 6.0%, and false positivity 0.0%. The overall diagnostic accuracy was 96.8%. Sensitivity of metastatic carcinoma was 98.0% and that of malignant lymphoma was 87.9%. False negative cases included one metastatic carcinoma and four malignant lymphomas. The aspirates of metastatic carcinoma with false negativity exhibited a diffuse smear of keratin debris without viable cells, which led to the difficulty in differentiation from benign epithelial cyst. The cases of malignant lymphoma with false negative diagnosis were two Hodgkin diseases, one Lennert's lymphoma, and one peripheral T cell lymphoma in the histologic sections. On the analysis of 39 cases of tuberculosis, 17 cases (43.6%) were diagnosed as tuberculosis, 4 (10.3%) as granulomatous lymphadenitis, 3 (7.7%) as necrotizing lymphadenitis, and 15 (38.5%) as reactive hyperplasia or pyogenic inflammation. Sensitivity of tuberculosis was 53.9%. In conclusion, lymph node FNAC is an excellent non-invasive diagnostic tool for the diagnosis of metastatic carcinoma. The diagnostic accuracy of malignant lymphoma could be improved with flow cytometry or polymerase chain reaction for antigen receptor genes. For the FNAC diagnosis of tuberculosis, AFB stain, culture, and PCR would be helpful as adjuvant techniques.