Dr Francis Hall is Head of the Department of Otolaryngology Head and Neck Surgery at Counties Manukau DHB. He has a private practice in Auckland. He is a New Zealand trained ORL head and neck surgeon with extensive additional overseas training in head and neck surgery in Toronto, Sydney and Melbourne. He worked for five years as a head and neck / thyroid surgeon at Henry Ford Hospital in Detroit. He is an accomplished writer and presenter and loves to share his experiences with fellow specialists and general practitioners.
An increasingly common problem
Thyroid nodules are very common, and more common in women with some estimates of palpable thyroid nodes occurring in 6% of the female population and 1.5% of the male population. Ultrasound detects thyroid nodules in 19-67% of the population with 5-10% being malignant.
Symptoms
Generally, the larger the thyroid nodule the more likely it is to cause compressive symptoms such as a pressure feeling, tightness or a lump in the neck. Thyroid nodules frequently cause no symptoms.
Nodules less than 2cm in size seldom cause symptoms.
If a nodule gets very large it may cause compression of the trachea resulting in shortness of breath on exertion and when lying down. Large thyroid nodules may also cause superior vena cava syndrome with restriction of venous drainage from the head and neck. This is most noticeable when the arms are raised in such activities as hanging out the washing. Patients may go red in the face when doing such activities (positive Pemberton’s sign).
Ultrasound Scans
A common scenario is a patient complains of a feeling of a lump in the neck, an ultrasound is requested, and this shows small thyroid nodules and a normal size thyroid. In this situation, thyroidectomy is unlikely to cure the patient’s symptoms.
An ultrasound scan of the thyroid and thyroid function tests should be requested on all patients with a suspected nodule in the thyroid gland.
The majority of patients with a thyroid nodule are euthyroid.
If the patient is hyperthyroid (high fT4 and low TSH), then referral to an endocrinologist and / or starting the patient on carbimazole is appropriate.
TIRADS Classification System
Ultrasound is used to categorise thyroid nodules according to the tirads system. This system categorises nodules according to their composition (solid, cystic,..), echogenicity (hypoechoic, isoechoic,..), shape, margin and echogenic foci. Points are given for each of these characteristics and recommendations are made depending on the size and tirads classification.
For example, FNA is recommended for a 1.5cm tirads 4 nodule, while ultrasound surveillance is recommended for a 2cm tirads 3 nodule.
A 4cm tirads 2 nodule requires no follow up. It is important to remember that these recommendations are for asymptomatic euthyroid patients.
The incidence of malignancy increases with a higher tirads classification as follows:
| Tirads | Description | Risk of malignancy |
| 1 | benign | 0.3% |
| 2 | benign | 1.5% |
| 3 | Mildly suspicious for malignancy | 4.8% |
| 4 | Moderately suspicious for malignancy | 9.1% |
| 5 | Highly suspicious for malignancy | 35% |
Basically, the size and tirads score determines which patients need an FNA and which patients need ultrasound surveillance.
Ultrasound Guided FNA (Fine Needle Aspiration)
It is recommended that fine needle aspiration (FNA) of thyroid nodules is done under ultrasound guidance.
FNA cytology results are classified according to the Bethesda system as follows:
| Bethesda | Description | Risk of malignancy |
| 1 | Non diagnostic | 12% |
| 2 | Benign | 2% |
| 3 | Atypia of undetermined significance (AUS) | 16% |
| 4 | Follicular neoplasm | 23% |
| 5 | Suspicious for malignancy | 65% |
| 6 | Malignant | 94% |
Surgery Recommendations
Patients with significant symptoms usually benefit from surgery, no matter what the tirads and Bethesda classification of the thyroid nodule are.
For patients with no symptoms and thyroid nodules, treat along the following guidelines:
Bethesda 1: Perform ultrasound guided core needle biopsy and treat according to result
Bethesda 2: No treatment
Bethesda 3: Consider surgery (especially if high tirads score)
Bethesda 4: Strongly consider surgery
Bethesda 5: Surgery
Bethesda 6: Surgery
RFA (Radio Frequency Ablation)
Patients with symptomatic Bethesda 2 nodes can also be treated with radiofrequency ablation of the nodule. This is a simple procedure done under ultrasound guidance and local anaesthesia. This is a scarless procedure that treats only the thyroid nodule.
More about radiofrequency ablation in next month’s edition of GP Voice.
References:
- Ali SZ, et al. Thyroid 2023; 33: 1039-1044. The 2023 Bethesda System for Reporting Thyroid Cytopathology.
- Tessler FN, Middleton WD, Grant EG, Hoang JK, Berland LL, et al. ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of the ACR TI-RADS Committee. (2017) Journal of the American College of Radiology : JACR. 14 (5): 587-595. doi:10.1016/j.jacr.2017.01.046– Pubmed
- Middleton WD, Teefey SA, Reading CC, et al. Mult institutional Analysis of Thyroid Nodule Risk Stratification Using the American College of Radiology Thyroid Imaging Reporting and Data System. (2017) American Journal of Roentgenology. 208 (6): 1331-1341. doi:10.2214/AJR.16.17613– Pubmed