Giblett, N.1; Muzaffar, S.J.1; Best, J.E.2 ; Sharma, N.1; Momtahan, N.3; Jayaram, S.4
1 Specialist Registrar in Otolaryngology, University Hospitals Birmingham, Birmingham, UK
2 Specialist Registrar in Clinical Oncology, Yorkshire Rotation, York, UK
3 Consultant Pathologist, City Hospital, Birmingham, UK
4 Consultant ENT Surgeon, City Hospital, Birmingham, UK
Background: Fine needle aspiration cytology (FNAC) forms part of routine work-up for any thyroid nodule in the UK. Whilst cytological analysis is less precise than histological assessment it is quick, easy to perform and may avoid the need for invasive investigation or unnecessary surgical risk.
This retrospective study compared pre-operative FNAC with post-operative histology results to establish the accuracy of diagnosis and malignancy rates.
Methods: 661 consecutive cases of thyroid specimens were assessed from the histology database of an inner city, single centre UK hospital. The results were then matched with the patient’s respective pre-operative FNAC results and compared to both British and American guidelines.
Results: In total 661 patients were identified as having thyroid surgery with available histology. 470 of these histological specimens had a preceding FNAC, 3 were excluded because of unavailable Thy rating. Of these 467; Thy1:151, Thy1c:14, Thy2:179, Thy2c:10, Thy3:54, Thy3a:17, Thy3f:18, Thy4:18, and Thy5:6.
Histological malignancy rates were as follows; Thy1:19.2%, Thy1c:21.4%, Thy2:12.3%, Thy2c:50%, Thy3:29.6%, Thy3a:64.7%, Thy3f:50%, Thy4:88.9% and Thy5:100%.
Discussion: Thy4 and Thy5 have a high specificity for malignancy and should be treated aggressively. Thy3 has an overall malignancy rate of 39.3% and therefore supports current practice of diagnostic hemi-thyroidectomy. Thy2 has a malignancy risk of 14.21% and should be closely correlated with ultrasound guidance.
Conclusion: Overall rates of malignancy varied considerably from those published and therefore each centre should quote a local rate of malignancy during patient counselling.
1. Royal College of Pathologists. Guidance on the reporting of thyroid cytology specimens. London; 2009.
2. Royal College of Physicians. Guidelines for the management of thyroid cancer. 2nd Ed. London; 2007.
3. British Thyroid Association. Guidelines for the management of thyroid cancer. 3rd Ed. 2014.
4. Haugen, Bryan R., et al. (2016) 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer: the American Thyroid Association guidelines task force on thyroid nodules and differentiated thyroid cancer. Thyroid. 26(1), 1-133.