What is the difference between a thyroid nodule and a multinodular goitre?

A thyroid nodule is a localised “swelling” within the thyroid gland. Sometimes this occurs as a single swelling in an otherwise normal gland. "If multiple nodules are found within the same thyroid gland, it is known as a multinodular goitre," says doctors from the Department of Endocrinology at Singapore General Hospital, a member of the SingHealth​ group.

What causes thyroid nodules?

Most are either simple “overgrowths” of normal thyroid tissue, fluid containing cysts or slowly growing benign tumours called adenomas. A small percentage of these nodules can be cancerous. The risk of thyroid cancer is higher if you have a history of radiation to the head and neck for other medical conditions, or if you have a family history of thyroid cancer.

What causes a multinodular goitre?

The most common cause of a multinodular goitre is iodine deficiency. However, it may still develop in some individuals who have enough iodine. In these people, the cause is not well understood.

How do I know if I have a thyroid nodule?

Most thyroid nodules do not cause symptoms. Thus, most people may only realise they have a thyroid nodule when it is large enough to be noticed in the mirror, or found by chance during a physical examination, or incidentally picked up during investigations such as an ultrasound, CT scan or PET scan.

Sometimes, bleeding into a thyroid cyst or nodule may cause a sudden painful swelling in the neck. Occasionally, advanced thyroid cancer may cause a hoarse voice or difficulty swallowing.

How do I know if I have a benign or cancerous thyroid nodule?

It is usually not possible to tell if a thyroid nodule is cancerous or benign based on a physical examination or blood tests. The two specialised tests which help us make this differentiation are an ultrasound of the thyroid, and a fine needle aspiration and biopsy (FNAB).

What is a fine needle aspiration and biopsy (FNAB)?

This is a simple procedure that can be performed in the doctor’s office. A tiny needle is introduced into the thyroid nodule to obtain cells which are then analysed in the laboratory. Most doctors take a few samples from the same nodule to increase its accuracy. The actual procedure generally only takes a few minutes, and you can usually return home or to work with no ill effects.

What are the possible results of a fine needle aspiration and biopsy?

The results may fall into three main categories – benign (non-cancerous), malignant (cancerous), or indeterminate. More than 80 per cent of all FNAs will be benign. Benign nodules can be left alone but should still be monitored for changes in size. Malignant thyroid nodules should be removed by surgery. Indeterminate FNAs refer to those that are neither clearly benign nor malignant, and no definite conclusion could be drawn from the FNA. Most of these nodules will still be benign, although your doctor will discuss its management with you. Occasionally, not enough cells may have been extracted to make a conclusive diagnosis. This is usually due to the nature of the thyroid nodule. In these cases, the FNA may need to be repeated.

How are thyroid nodules treated?

Most patients with benign thyroid nodules do not require any specific treatment, and are usually followed up once or twice a year for changes in size. If cancer is suspected, surgery will be recommended.

Do you know?

  • 50 per cent of those above the age of 60 may have a thyroid nodule
  • 80-90 per cent of all thyroid nodules are benign (non-cancerous)

Ref: V10