DNA flow-cytometry on fine needle aspiration cytology of lymph node: how helpful is it?

The diagnostic value of DNA content analysis by flow cytometry (FCM) has rarely been evaluated in combination with fine needle aspiration cytology (FNAC). In this present study, the value of DNA FCM in distinguishing malignant lesions from benign enlarged lymph nodes on FNAC material has been investigated. DNA FCM was done from FNAC materials of 58 cases of lymph node swellings Becton Dickinson's flow cytometer (USA) along with 'Cell Quest' program was used for the analysis of DNA ploidy and S & G2-M phase cells. There were 16 cases of reactive lymphoid hyperplasia, 8 cases of metastatic carcinoma and 34 cases of non Hodgkins lymphoma (NHL). DNA FCM showed 12 aneuploid case and 46 diploid case. All the cases with DNA aneuploidy were malignant. None of the benign cases showed aneuploidy on DNA aneuploidy were malignant. None of the benign cases showed aneuploidy on DNA histogram. Out of the 46 diploid cases, 11 cases showed high S & G2-M Phase cells (> 10%). Nine out of these 11 cases were malignant on FNAC. The sensitivity and specificity of DNA FCM were 50% and 87.5% respectively. None of the low grade NHL was detected by DNA FCM. In conclusion, DNA aneuploidy and high G2-M phase cells (> 10%) are good indicators of malignancy in lymph node aspirate. However DNA FCM is relatively costly and thereby its role as an adjunctive technique needs careful re-evaluation.