Regional audit into the indeterminate thy3f cytology thyroid nodules and their resulting histological malignancy rate at Luton & Dunstable Hospital and Lister Hospital


O Kenyon, A Shaladi, M Ally, V Blackabey, E Schechter, R Bance, D Ravichandran, P Loizou, G Mochloulis, P Kothari, Luton & Dunstable Hospital and Lister Hospital


Abstract: Fine needle aspiration cytology (FNAC) is a valuable investigation for thyroid nodules1. Thy3f grading is used when a follicular neoplasm is suspected however benign and malignant histology cannot be distinguished by cytology alone2.

We accessed all thyroid related cytology in Luton & Dunstable Hospital between October 2017 and January 2019, yielding 29 patients with Thy3f classifications of which final histology was available for 19 (66%). In Luton & Dunstable 15 patients had US grading available, comprising one U2 (benign), 13 (87%) were U3 (indeterminate), and one U4 (suspicious).


In Lister Hospital we identified all patients discussed at MDT with the term Thy3F From June 2014 to June 2017, yielding 46 patients, of which 41 patients had final histology (89%). All patients had US grading available: 6 were graded U2/U3, 32 (70%) were U3, 3 were U3/4, 4 were U4 and 1 were U4/5.


The histology ranged from follicular adenoma (with and without oncocytic changes); hypoplastic nodule with focus of micropapillary carcinoma; follicular carcinoma; papillary carcinoma; to a plasmacytoma (corresponding to the U2 grading).

We found a malignancy rate of 53% (10/19) in Luton & Dunstable Hospital and 54% (22/41) in Lister Hospital averaging 53.3%. This falls high within the quoted malignancy rates in the literature (18-54%)3 which may be due to the patient demographics and we plan to expand the time scale to capture more patient data.



[1] Bajaj, T., De M. & Thompson, A. (2006) Fine needle aspiration cytology in diagnosis and management of thyroid disease.  Journal of Laryngology and Otology, 120, 467-469

[1] Perros, P. et al (2014) British Thyroid Association Guidelines for the Management of Thyroid Cancer. Clinical Endocrinology, 81 (Suppl. 1), 1-122

[1] Alexander, V., Rudd, J., Walker, D. et al (2018) Thy 3F and 3a malignancy rate, a multisite regional retrospective case series. Annals of the Royal College of Surgeons of England, 100, 545-550