Ojidu, James1; Malik, Mohamed2; Dhanasekar, Ganapathy3.
1 Division of Endocrinology and Diabetes, Department of Medicine, Scunthorpe General Hospital, Northern Lincolnshire and Goole NHS Foundation Trust, Yorkshire, England, United Kingdom
2 Division of Endocrinology and Diabetes, Department of Medicine, Scunthorpe General Hospital, Northern Lincolnshire and Goole NHS Foundation Trust, Yorkshire, England, United Kingdom
3 Department of Otorhinolaryngology – Thyroid Surgery, Scunthorpe General Hospital, Northern Lincolnshire and Goole NHS Foundation Trust, Yorkshire, England, United Kingdom
Background: FNAC is currently the gold standard for preoperative diagnosis of clinically suspicious thyroid lesions. However, it has a reasonably low rate of definitive diagnosis meaning most diagnoses of thyroid cancer are made postoperatively. We aim to present our experience at a district general hospital.
Method: 76 thyroid surgeries performed between July 2013 and September 2016 were studied. Parameters were predetermined and in strict accordance with the 2014 British Thyroid Association guidelines.
Results: Mean patient age was 55.1 years and 80% were female. 100% (n=76) underwent preoperative FNAC: 35% (n=27) were non-diagnostic (Thy1), 15% (n=11) were non-neoplastic/benign (Thy2), 30% (n=23) had atypical features present (Thy3a), 16% (n=12) were follicular neoplasm suspected (Thy3f) and 4% (n=3) were suspicious of malignancy (Thy4). Overall false negative rate of 8% (n=6) and false positive rate 33% (n=25). 16% (n=6) of Thy1/Thy2 cases were diagnosed as cancer postoperatively. 60% correlation between FNAC and surgical histology.
Discussion: Radiologists should use ultrasound classification to stratify thyroid nodules as benign, suspicious or malignant based on ultrasound appearances U1-U5. This can be used to guide further investigation and management. Use of cytogenetic analysis and immunohistochemistry could enhance FNAC reporting. More ultrasound guided core biopsies could increase preoperative diagnostic accuracy.
Conclusion: Our results are comparable with both UK and international studies, regarding false negative rate (8% vs 1-10%). Also we observed the high rate of false positives in association with over reporting of Thy1 and Thy3a.
- Guidelines for the management of thyroid cancer, Third Edition, British Thyroid Association (2014)
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- Sukumaran R, Kattoor J. Fine needle aspiration cytology of thyroid lesions and its correlation with histopathology in a series of 248 patients. Indian association of surgical oncology. 2014.