Difference Between Thyroid Nodule and Cyst

The thyroid gland is an important part of the endocrine system, located in the neck, and responsible for producing hormones that regulate various body functions such as metabolism, heart rate, and body temperature. Sometimes, lumps or growths can develop on the thyroid gland and cause concern. Two common types of growths that can occur on the thyroid are thyroid nodules and cysts. Although these terms are often used interchangeably, there are significant differences between them.

What is Thyroid Nodule?

Thyroid nodules are big, painful lumps that can form on the thyroid gland. It's tough, uncomfortable, and sensitive to the slightest touch. These growths seldom progress to malignancy. A nodule on the thyroid often forms subcutaneously.

A thyroid nodule may be completely cystic if there are no solid components within the fluid. Complex thyroid nodules consist of both solid and liquid parts. Causes of thyroid nodules include thyroiditis, iodine shortage, thyroid adenoma, thyroid cyst, and malignancy.

Thyroid nodules are associated with a number of factors, including −

  • For women aged 30, 30% will have a thyroid nodule found.

  • Thyroid nodules affect significantly more females than males.

  • Ninety-five percent or more of thyroid nodules are benign, meaning they won't cause any harm if left alone.

  • Thyroid nodules are uncommon, and just 5-10% are malignant.

  • Thyroid nodules only affect 2%-4% of males.

  • Thyroid nodules become more common as people become older.

  • Pure cystic nodules of the thyroid (thyroid cysts) are normally harmless.

  • Thyroid nodules can be classified as either solid or cystic, with cystic nodules consisting of fluid and no tissue at all.

What is Cyst?

An air or liquid-filled bump that can form anywhere on the body is called a cyst. Thyroid cysts enlarge rapidly when they experience internal bleeding. Symptoms including discomfort, swallowing difficulties, and vocal cord constriction can develop if thyroid cysts are allowed to grow unchecked.

There is a 15% chance that these cysts may go away on their own. Thyroid cysts can range in size from extremely large to very small, sometimes appearing out of nowhere. Radioactive iodine, anti-thyroid medicines, and surgery are all options for dealing with thyroid cysts. Pure thyroid cysts smaller than or equal to 3 centimetres in diameter are tracked for progression. Aspiration and ethanol instillation are ablative methods that can be used for management.

Cysts of the thyroid gland that contain just fluid have a considerably lower probability of developing into thyroid cancer than those containing solid components.

Differences: Thyroid Nodule and Cyst

The following table highlights the major differences between Thyroid Nodule and Cyst −


Thyroid Nodule



Thyroid nodules are rarely malign and relatively common. A thyroid nodule is an elevated lump that usually develops or grows in your thyroid gland. A nodule is either filled with fluid or it can be solid.

Thyroid cysts are enlarged fluid-filled cavities that are usually less than 1 cm in size. Sometimes they are quite large and develop suddenly

Thyroid cysts are caused by degenerating thyroid adenomas. Cysts are usually benign (non-cancerous), but they occasionally contain malignant solid components. Fluids and solid components are mixed in thyroid cysts.


Thyroid nodules produce additional thyroxine (a hormone the thyroid gland secretes into the bloodstream). This additional extra thyroxine can cause symptoms of hyperthyroidism such as:

  • Elevated perspiration

  • An enlarged thyroid gland, known as a goitre

  • Irregular and rapid heartbeat

  • Swallowing difficulties

  • Muscle weakness

  • Breathing difficulties

  • Unexplained weight loss

  • Tremor

  • Nervousness

  • A noticeable lump in the neck

  • Pain

  • Change in voice

  • Difficulty in swallowing


  • Overgrowth of normal thyroid tissue (stronggenetic basis)

  • Hashimoto’s disease – It is a condition in which your immune system attacks your thyroid, a small gland at the base of your neck below your Adam’s apple

  • Thyroid cancer

  • Chronic inflammation of your thyroid

  • Iodine deficiency

  • Structural abnormalities of the thyroid gland from birth

Fluid-filled cavities (cysts) in the thyroid are caused by degenerating thyroid adenomas. The fluid is usually mixed with some solid components in thyroid cysts.

Specific characteristic

It is filled with solid materials

It is filled with fluids

Pus filled

No pus

No pus but filled with fluid


  • Keloid scars- Nodular lesions caused due to repair mechanisms meant to heal injuries to the body organs

  • Pulmonary modules – nodular lesions in inflammatory conditions like rheumatoid arthritis

  • Granulomas – nodular lesions occurring in conditions like Tuberculosis

  • Sebaceous cysts – formed over the skin and possess a bluish discoloration. Surgery is mostly recommended in these kinds of cysts in order to prevent them from getting an infection.

  • Dermoid cysts – A sac-like non-cancerous lump in the skin

  • Painful Bartholin cysts – these develop in the females in Bartholin glands

  • Cysts in the internal organs such as thyroid gland, ovaries, and kidney


Thyroid nodules and cysts are two distinct types of growths that can occur on the thyroid gland. Thyroid nodules are solid lumps or growths, while cysts are fluid-filled sacs. Both types of growths can be benign or malignant and require proper diagnosis and treatment.

It is important for individuals to be aware of the difference between these two conditions and seek medical attention if they suspect the presence of a growth on their thyroid.

Updated on: 10-Apr-2023


Kickstart Your Career

Get certified by completing the course

Get Started