Introduction: Ultrasound (US) is an extremely sensitive examination for thyroid nodules. Fine needle aspiration (FNA) cytology samples taken with ultrasound guidance, increases accuracy and reduces rates of unsatisfactory samples1. In addition, the immediate assessment of the sample for adequacy by onsite cytopathology is shown to reduce inadequacy rates by most reports2.
Aim: The aim of this study was to compare the inadequacy (Thy1) rates between US guided FNA with onsite histopathology and palpation guided (Free-hand) FNAs.
Methods: Retrospective review of all FNAs performed during five years period between 2008 and 2012.Data were collected from the pathology department laboratory and the radiology computerised systems.
Results: Five hundred and sixty seven thyroid FNAs were performed on 433 patients during this period. The cytological diagnoses were as follows: Thy1 (non-diagnostic) in 63 (11.1%) cases, Thy2 (benign) in 424 (74.8%) cases, Thy3 (follicular lesion/neoplasm) in 54 (9.5%) cases, Thy4 (suspicious for malignancy) in 9 (1.6%) and Thy5 (malignant) in 17 (3%) cases. Out of 531 cases were the guidance method was documented, 423 (79.7%) were US guided with onsite cytopathology evaluation and 108 (20.3%) were free-hand. Inadequacy rate (Thy1) was significantly lower in the US guided FNA (37/423, 8.7%) compared to the free-hand aspirates (17/108, 15.7%), (P<0.05).
Conclusion: FNAs done under US guidance combined with onsite cytopathology have significantly lower in-adequacy rates compared to free-hand FNA.This method should be used in all cases to improve adequacy and reduce patient distress and cost.
References: 1. Peros P, et al. Guidelines for the management of thyroid cancer. Clinical Endocrinology, 2014; 81: 112.
2. Poller D N, et al. Thyroid FNAC cytology: can we do it better? Cytopathology 2008 Feb; 19(1):410.