Case 17.3 – Thyroid Swelling/Goitre [SDL]

Symptoms to assess:

• Symptoms of thyrotoxicosis/hyperthyroidism (see previous case)
• Dysphagia
• Stridor (mediastinal compression)
• Hoarseness (recurrent laryngeal nerve palsy) - may indicate anaplastic thyroid malignancy or a massive goitre

• Palpation: Size, shape, consistency, tenderness, mobility
• Percussion: For retrosternal goitre
• Auscultation: Bruit (increased blood supply in hyperthyroidism)
• Pemberton's sign: Thoracic inlet obstruction due to retrosternal mass

Diffuse goitre

• In the absence of thyrotoxicosis or hypothyroidism a diffuse goitre rarely needs further investigation or treatment
• Exception: if very large and causing cosmetic symptoms or compression of other local structures (resulting in stridor or dysphagia)
• The presence of autoantibodies may support the diagnosis of Graves' disease or Hashimoto's thyroiditis
• Their absence in a younger patient suggests a simple goitre
• Thyroxine therapy is sometimes justified in an attempt to shrink the goitre

Multinodular goitre

• Usually diagnosed in patients presenting with thyrotoxicosis, a large goitre with or without tracheal compression, or sudden painful swelling caused by haemorrhage into a nodule or cyst
• The goitre is nodular or lobulated on palpation and may extend retrosternally
• Not all multinodular goitres causing thyrotoxicosis are easily palpable
• Very large goitres may cause mediastinal compression with stridor, dysphagia and obstruction of the superior vena cava
• Hoarseness due to recurrent laryngeal nerve palsy can occur, but is far more suggestive of thyroid carcinoma
• Diagnosis: Confirmed by radioisotope thyroid scan and/or ultrasonography
• Assessment of compression: Flow-volume loop is a good screening test for significant tracheal compression
• Imaging if intervention contemplated: Chest X-ray may be helpful, but CT or MRI of the thoracic inlet is optimal to quantify the degree of tracheal displacement or compression and the extent of retrosternal extension
• Dominant nodule: In those with a 'dominant', 'cold' nodule, fine needle aspiration is indicated to exclude thyroid cancer

Solitary thyroid nodule

• Important to determine whether the nodule is benign (e.g. cyst or colloid nodule) or malignant
• Rarely possible to make this distinction on clinical grounds alone
• Presence of cervical lymphadenopathy increases the likelihood of malignancy
• High suspicion scenarios:
  • Solitary nodule presenting in childhood or adolescence, particularly if there is a past history of head and neck irradiation
  • Presenting in the elderly
• Rare: Secondary deposit from a renal, breast or lung carcinoma presents as a painful, rapidly growing solitary thyroid nodule

• Simple goitre usually presents between the ages of 15 and 25 years, often during pregnancy
• Tends to be noticed, not by the patient, but by friends and relatives
• Occasionally, there is a tight sensation in the neck, particularly when swallowing
• The goitre is soft and symmetrical and the thyroid is enlarged to two or three times its normal size
• There is no tenderness, lymphadenopathy or overlying bruit
• Concentrations of T₃, T₄ and TSH are normal
• No thyroid autoantibodies are detected in the serum
• No treatment is necessary and in most cases the goitre regresses
• In some, however, the unknown stimulus to thyroid enlargement persists and, as a result of recurrent episodes of hyperplasia and involution during the following 10-20 years, the gland becomes multinodular with areas of autonomous function

Natural history progression:

From a clinical standpoint, the possibility of neoplastic disease is of major concern in patients who present with thyroid nodules. Fortunately, the overwhelming majority of solitary nodules of the thyroid prove to be localized, non-neoplastic conditions (e.g. nodular hyperplasia, simple cysts, or foci of thyroiditis) or benign neoplasms such as follicular adenomas. In fact, benign neoplasms outnumber thyroid carcinomas by a ratio of nearly 10:1. Carcinomas of the thyroid are thus uncommon, accounting for well under 1% of solitary thyroid nodules. Moreover, most are indolent, permitting a 90% survival at 20 years.

Several clinical criteria might provide a clue to the nature of a given thyroid nodule:

• Solitary nodules, in general, are more likely to be neoplastic than are multiple nodules
• Nodules in younger patients are more likely to be neoplastic than are those in older patients
• Nodules in males are more likely to be neoplastic than are those in females
• A history of radiation treatment to the head and neck region is associated with an increased incidence of thyroid malignancy
• Nodules that take up radioactive iodine in imaging studies (hot nodules) are more likely to be benign than malignant

Such general trends and statistics, however, are of little significance in the evaluation of a given patient, in whom the timely recognition of a malignancy, however uncommon, can be life-saving. Ultimately, it is the morphologic evaluation of a given thyroid nodule, in the form of fine-needle aspiration biopsy and histologic study of surgically resected thyroid parenchyma, that provides the most definitive information about its nature.

* Patients with medullary carcinoma as part of multiple endocrine neoplasia type 2 may present in childhood.

Key points about thyroid malignancies:

• Papillary carcinoma is the most common (70%), presents in younger adults (20-40), and has excellent prognosis (95% 20-year survival)
• Follicular carcinoma is less common (10%), presents in middle age (40-60), with moderate prognosis (60% 20-year survival)
• Anaplastic carcinoma is rare (5%), presents in elderly (\>60), with very poor prognosis (\<1% 20-year survival)
• Medullary carcinoma arises from parafollicular C cells, may be sporadic or part of MEN type 2

Indications for surgery:

• To relieve the pressure symptoms of a large goitre
• For substernal goitre
• To rule out cancer when there are localized areas of hardness or rapid growth