Thyroid diseases can generally be classified into disorders affecting thyroid structure, such as multinodular goitre, and disorders of thyroid function, such as hyperthyroidism or hypothyroidism. But thyroid diseases that may require surgical intervention are categorized as follows: embryological development disorders; benign thyroid nodules; multinodular goitre; thyroid cancer; thyrotoxicosis; and, thyroiditis.
Embryological Development Disorders
During embryological development, the thyroid gland descends to its place at the base of the throat. This process may leave behind remnants of thyroid tissue anywhere in the thyroglossal tract; on some occasions this may lead to a cyst in the thyroglossal duct. These cysts are common among children and adolescent, and are usually confirmed by the doctors through fine-needle aspiration cytology (FNAC) before surgical excision is done.
Benign Thyroid Nodules
A benign thyroid nodule can be a simple thyroid cyst, benign follicular adenoma or solitary colloid nodule. The common sign of nodules is the swelling of the neck, which moves on swallowing. Other symptoms of benign thyroid nodules may include a voice hoarsened by pressure on the larynx or persistent cough. To rule out toxic nodules, thyroid function tests such as TSH, free T4 and T3, are often performed in all patients. Surgery is only performed when there is a finding of cancerous nodules, or thyrotoxicosis.
Multinodular Goitres
Multinodular goitre may develop after repeated cycles of hyperplasia, nodule formation, degeneration and fibrosis throughout the thyroid. Generally, multinodular goitre appears as an asymptomatic mass, or may cause obstructive symptoms in the trachea, oesophagus, or the recurrent laryngeal nerve. The condition requires thyroid function tests for evaluation. FNAC of the dominant nodule(s) will help screen for malignancy and a CT scan will assess tracheal compression and restrosternal extension. Surgery may be needed to treat obstructive symptoms, thyrotoxicosis, restrosternal extension, and suspicious or malignant changes on FNAC. A strong family history of thyroid cancer or a personal history of head and neck irradiation may also argue for surgery.
Thyroid Cancers
Thyroid cancer can arise from various cells in the gland, each one giving rise to a different form. Thyroid cancer commonly appears as a single thyroid nodule or a dominant nodule in a multinodular goitre. The cancer may also present a metastatic disease, such as bony metastases from follicular cancer, or lymphangitic lung involvement from papillary cancer. Depending on the presentation, the most useful test is FNAC, but CT scanning helps determine the extent of tumour and lymph node involvement. Except for very-low-risk follicular or papillary cancer, all other thyroid cancers are treated by total removal of the thyroid along with the involved lymph nodes.
Thyrotoxicosis
Thyrotoxicosis can occur in Graves’ disease, toxic multinodular goitre (Plummer’s disease), toxic follicular adenoma or in the initial stages of thyroiditis. Thyrotoxicosis is usually accompanied by signs and symptoms of thyroid overactivity, including heat intolerance, sweating, weight loss and anxiety. Elevated levels of free T3 or free T4, along with suppressed TSH, will support a diagnosis of thyrotoxicosis.
Thyroiditis
Thyroiditis is further classified as to origins: lymphocytic (Hashimoto’s), subacute, acute (bacterial) or fibrosing. Two types are the most common. Lymphocytic is an autoimmune condition often corollary to Graves’ disease, and subacute, which is post-viral phenomenon. Lymphocytic thyroiditis may present with hyperthyroidism (early phase) or hypothyroidism (late phase), or with a moderate goitre (nodular or diffuse). Subacute thyroiditis usually presents with an enlarged and very tender gland accompanied by headache, malaise and weight loss. Thyroid function tests will measure the level of thyroid activity. Lymphocytic thyroiditis with persistent or suspicious nodules, or for pressure symptoms, may require surgery, which will be difficult to perform because of the firm, nonpliable nature of the gland.
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