Thyroid Neoplasms

Definition

Thyroid neoplasms are abnormal growths or tumours that develop in the thyroid gland, which is located at the front of the neck. These neoplasms can be benign (non-cancerous) or malignant (cancerous).

Aetiology

The causes of thyroid neoplasms include:

Genetic Factors: Family history of thyroid cancer or genetic syndromes such as Multiple Endocrine Neoplasia (MEN) type 2 and familial medullary thyroid carcinoma.
Radiation Exposure: Previous exposure to ionising radiation, especially during childhood.
Chronic Thyroiditis: Conditions such as Hashimoto's thyroiditis.

Pathophysiology

Thyroid neoplasms can be classified based on their cellular origin and behaviour:

Benign Neoplasms: Includes thyroid adenomas which are usually encapsulated and do not invade surrounding tissues.
Malignant Neoplasms: Includes different types of thyroid cancer such as:
- Papillary Thyroid Carcinoma: The most common type, often slow-growing and typically has a good prognosis.
- Follicular Thyroid Carcinoma: The second most common type, can spread to distant organs such as the lungs and bones.
- Medullary Thyroid Carcinoma: Arises from parafollicular cells (C cells) and can be associated with genetic syndromes.
- Anaplastic Thyroid Carcinoma: A rare, aggressive form of thyroid cancer with a poor prognosis.

Risk Factors

Family history of thyroid cancer or genetic syndromes
Exposure to ionising radiation, especially during childhood
Female gender (more common in women)
Age (most common in adults aged 30-60)
Chronic thyroiditis (e.g., Hashimoto's thyroiditis)

Signs and Symptoms

Symptoms of thyroid neoplasms can vary depending on the type and size of the tumour:

Neck lump or swelling
Difficulty swallowing or breathing
Hoarseness or voice changes
Persistent cough not related to a cold
Enlarged lymph nodes in the neck
In some cases, thyroid neoplasms may be asymptomatic and discovered incidentally during imaging for other conditions.

Investigations

Clinical history and physical examination
Thyroid function tests: TSH, free T4, and free T3 levels to assess thyroid function
Ultrasound of the neck: To evaluate the thyroid gland and detect nodules
Fine-needle aspiration biopsy (FNAB): To obtain a sample for cytological examination
Radioiodine scan: To differentiate between functional (hot) and non-functional (cold) nodules
Computed tomography (CT) or magnetic resonance imaging (MRI): For further assessment and staging if malignancy is suspected
Genetic testing: For patients with a family history or clinical suspicion of hereditary thyroid cancer syndromes

Management

Primary Care Management

Referral to endocrinologist: For diagnosis confirmation and management plan
Monitoring: Regular follow-up for patients with benign thyroid nodules to monitor for changes in size or function
Education: Informing patients about the condition, potential symptoms, and the importance of follow-up

Specialist Management

Surgery: Thyroidectomy (partial or total) is the primary treatment for most thyroid cancers. Lobectomy may be considered for small, low-risk cancers.
Radioactive iodine therapy: Used after surgery to ablate any remaining thyroid tissue and treat metastatic disease.
Thyroid hormone replacement: To maintain normal thyroid hormone levels and suppress TSH in patients who have had a thyroidectomy.
External beam radiotherapy: For advanced or inoperable thyroid cancers.
Targeted therapy and chemotherapy: For advanced, metastatic, or refractory thyroid cancers.
Regular monitoring: Follow-up with ultrasound and serum thyroglobulin levels to detect recurrence.

Example Management for Thyroid Neoplasms

A patient diagnosed with papillary thyroid carcinoma presenting with a neck lump should be referred to an endocrinologist. Initial management includes surgical resection with a thyroidectomy. Post-surgery, radioactive iodine therapy may be used to ablate any remaining thyroid tissue. Thyroid hormone replacement therapy is necessary to maintain normal thyroid hormone levels and suppress TSH. Regular monitoring with neck ultrasound and serum thyroglobulin levels is essential to detect any recurrence. The patient should be educated on the importance of follow-up and recognising symptoms of recurrence.

References

NICE. (2024). Thyroid Cancer: Diagnosis and Management. Retrieved from NICE
NHS. (2023). Thyroid Cancer. Retrieved from NHS
American Thyroid Association (ATA). (2022). Guidelines for the Management of Thyroid Nodules and Differentiated Thyroid Cancer. Retrieved from ATA
British Thyroid Foundation. (2021). Thyroid Cancer Information. Retrieved from British Thyroid Foundation