- Thyroid lumps (nodules) may occasionally represent a primary thyroid malignancy, although most are benign.
- Very large thyroid lumps may rarely lead to tracheal compression and airway symptoms.
- A quickly-expanding (over weeks), firm thyroid mass may very rarely be due to thyroid lymphoma or anaplastic carcinoma.
Why is this important?
Lumps in the thyroid are a common reason for referral to a head-and-neck clinic. A significant majority are benign (90-95%), but all are assessed thoroughly to rule out malignancy.
When to involve the ENT registrar
- Immediately: Discuss infected neck lumps and any neck lump that may be objectively (i.e. noisy breathing) compressing the airway.
- Next working day: New thyroid masses should be referred to and assessed in a multidisciplinary head-and-neck outpatient clinic.
Patients may present having become aware of a lump in the neck – thyroid nodules will be felt quite low down in the anterior neck, and will rise on swallowing. Some patients will be referred from an endocrinology team, and a significant minority of nodules may have been detected incidentally on imaging.
Rarely, a large lump may cause cough, shortness of breath or stridor due to compression of the underlying trachea. In some cases of malignancy, direct involvement of the recurrent laryngeal nerve may cause hoarseness.
Thyroid lumps can be solitary or multiple. They may rarely be associated with hyperthyroidism (eg a single “toxic” nodule), or more commonly hypothyroidism (especially in a degenerative multinodular goitre). However a majority of patients will be euthyroid.
Most thyroid nodules are adenomas. These are benign, and are extremely common, especially with advancing age.
Malignant thyroid tumours are mostly adenocarcinomas, most of which fall into four categories:
- Papillary carcinoma (65%): the most common thyroid malignancy. Has an excellent prognosis if diagnosed early, especially in young females.
- Follicular carcinoma (30%): also associated with a good prognosis. Cannot be differentiated from follicular adenoma with fine-needle aspirate alone so diagnostic hemithyroidectomy is usually required.
- Medullary carcinoma (3%): less common, may be associated with MEN-2 syndrome.
- Anaplastic carcinoma (1%): rare and highly aggressive. Most tumours are unresectable and have a very poor prognosis.
Other rarer thyroid malignancies include lymphoma, squamous cell carcinoma and sarcoma.
Like other head-and-neck cancers, thyroid malignancies are staged using the TNM system.
The investigation and management of thyroid nodules is guided by the British Thyroid Association guidelines, although certain elements will vary by region/MDT.
Thyroid nodules over 1 cm in size are generally felt to warrant further investigation. Initially nodules are assessed with ultrasound, and fine-needle aspiration cytology (FNAC) is obtained if necessary. Further imaging with CT is occasionally required.
The radiologist will grade the ultrasound appearance of a nodule from U2-5. Nodules that are U2 do not generally require FNAC - if there are no other features of concern the patient can be discharged without further investigation. Nodules that are U3-5 are subjected to FNAC.
Both the ultrasound scan and the results of any FNAC give information about the probability of a nodule being malignant. These results must be interpreted together, and in the light of the patient’s history, risk factors and examination findings.
Cytology results are graded according to the Thy system:
- Thy 1: insufficient sample.
- Thy 2: very likely to be benign.
- Thy 3a: indeterminate, a chance of malignancy of c. 20%
- Thy3f: follicular neoplasm, a chance of malignancy of c. 30% (these figures vary by MDT)
- Thy 4: likely to be malignant
- Thy 5: almost certainly malignant
All patients must have their vocal cord mobility assessed by flexible nasendoscopy prior to surgery.
The management of a thyroid nodule may be conservative, medical or surgical. Policies vary slightly between departments, but in general:
- Thy 1: repeat FNAC to obtain a diagnostic sample.
- Thy 2: conservative management. Surgery or repeated investigation may however be indicated for other factors raising possibility of malignancy such as rapid enlargement, family history or suspicious ultrasound findings. Excision can be performed for cosmesis or pressure symptoms.
- Thy3a: discuss at MDT. The options are to repeat investigations or to perform a diagnostic hemithyroidectomy.
- Thy 3f: discuss at MDT. Usually diagnostic hemithyroidectomy is performed for histological diagnosis.
- Thy 4: discuss at MDT. The options are diagnostic/therapeutic hemithyroidectomy, or total thyroidectomy.
- Thy 5: discuss at MDT. The options are therapeutic hemithyroidectomy or total thyroidectomy depending on tumour size/patient risk factors.
Hemithyroidectomy may be sufficient treatment for a small malignancy in a patient without other risk factors. In other patients, a completion thyroidectomy may be performed after a diagnostic hemithyroidectomy when malignancy is confirmed.
If a patient requires total thyroidectomy for their malignancy, they may also require radioactive iodine ablation. This is an oncology/MDT decision and is
All management decisions are made through a thyroid multidisciplinary team (MDT), and must take account of the patient’s comorbidities and wishes.
Page last reviewed: 27 July 2018