Malignancy Risk Analysis in Patients with Inadequate Fine Needle Aspiration Cytology

• Published in: PloS one Vol. 7; no. 11; p. e49078
• Main Authors: Al Maqbali, Talib, Tedla, Miroslav, Weickert, Martin O, Mehanna, Hisham
• Format: Journal Article
• Language: English
• Published: Public Library of Science 19.11.2012
• Subjects: Risk assessment; Risk factors; Thyroid diseases
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0049078

Thyroid fine needle aspiration cytology (FNAC) is the standard diagnostic modality for thyroid nodules. However, it has limitations among which is the incidence of non-diagnostic results (Thy1). Management of cases with repeatedly non-diagnostic FNAC ranges from simple observation to surgical intervention. We aim to evaluate the incidence of malignancy in non-diagnostic FNAC, and the success rate of repeated FNAC. We also aim to evaluate risk factors for malignancy in patients with non-diagnostic FNAC. Retrospective analyses of consecutive cases with thyroid non diagnostic FNAC results were included. Out of total 1657 thyroid FNAC done during the study period, there were 264 (15.9%) non-diagnostic FNAC on the first attempt. On repeating those, the rate of a non-diagnostic result on second FNAC was 61.8% and on third FNAC was 47.2%. The overall malignancy rate in Thy1 FNAC was 4.5% (42% papillary, 42% follicular and 8% anaplastic), and the yield of malignancy decreased considerably with successive non-diagnostic FNAC. Ultrasound guidance by an experienced head neck radiologist produced the lowest non-diagnostic rate (38%) on repetition compared to US guidance by a generalist radiologist (65%) and by non US guidance (90%). There is a low risk of malignancy in patients with a non-diagnostic FNAC result, commensurate to the risk of any nodule. The yield of malignancy decreased considerably with successive non-diagnostic FNAC.