A nodule is a growth of abnormal tissue. Nodules can develop just below the skin. They can also develop in deeper skin tissues or internal organs.

Dermatologists use nodules as a general term to describe any lump underneath the skin that’s at least 1 centimeter in size. It’s not a specific diagnosis. Rather, it’s used to communicate to other dermatologists what they see.

The thyroid gland may develop nodules. Nodules are often used to refer to enlarged lymph nodes (lymphadenopathy).

Areas where lymphadenopathy may form (and thus nodules may be seen) include the:

A nodule feels like a hard lump in the skin. It’s often visible.

Depending on where the nodule is located and its cause, additional symptoms may be present. For example:

  • A nodule on the thyroid may affect swallowing.
  • A nodule in the abdomen may cause abdominal discomfort.
  • A nodule on a vocal cord may change the sound of your voice.

Sometimes, you can have a nodule without any other symptoms.

Lymph node nodules

Lymph nodes can become enlarged (lymphadenopathy). When enlarged, they can be seen as a nodule under the skin, or as a nodule on an imaging test, such as a chest X-ray.

Lymph nodes are small, oval-shaped organs located throughout the body. They play an important role in your body’s immune system and may temporarily swell when you’re sick.

Lymph nodes can also enlarge in a type of cancer known as lymphoma. If you have any persistently enlarged lymph nodes, have your doctor evaluate them.

Swollen lymph nodes can sometimes be found in the:

  • armpits
  • groin
  • head and neck region

Vocal cord nodules

Vocal cord nodules are noncancerous. Overuse or misuse of the voice often causes them. Stomach acid irritating your voice box is another possible cause.

Lung nodules

Lung nodules typically range from 0.2 to 1.2 inches in size, but they can be larger. They may represent swollen lymph nodes in some instances. There are several reasons why a nodule forms in the lungs, such as infection.

Noncancerous nodules usually don’t require treatment. Nodules bigger than 1.2 inches may be more likely to be cancerous. Your doctor will come up with a plan with you to monitor these nodules and determine when a biopsy is necessary.

Thyroid nodules

Thyroid nodules have a variety of causes. The following are common types of thyroid nodules:

  • Colloid nodules develop from a lack of iodine, which is a mineral essential to the production of thyroid hormones. These growths are noncancerous, but they may be large.
  • Hyperfunctioning thyroid nodules produce thyroid hormone, which may cause hyperthyroidism (overactive thyroid).
  • Multinodular goiter occurs when the thyroid gland forms multiple nodules, which grow over time. It can occur due to a lack of iodine in your diet, but most people with goiters have a thyroid gland that functions normally.
  • Thyroid cancer is another cause of thyroid nodules, but most thyroid nodules aren’t cancerous. Research estimates 5 percent of biopsied thyroid nodules are cancerous.

Some causes of nodules are:

Infections

Nodules can also develop in internal tissues. Inflammation often occurs due to an infection or an autoimmune reaction, which occurs when your body overreacts to its own tissues.

For example, a granuloma is a small clump of cells that forms when tissue is inflamed. Granulomas commonly form in the lungs, but they can develop in other places as well.

Thyroid hormones

Your thyroid gland is at the base of your neck, just above your collarbone. The thyroid gland produces hormones that regulate your metabolism and growth.

Hyperthyroidism is a condition in which your thyroid produces too much thyroid hormone. Sometimes, nodules form that produce excess thyroid hormone, leading to hyperthyroidism.

Iodine deficiency

Iodine is a mineral necessary for the production of thyroid hormones. When your body doesn’t get enough iodine, thyroid nodules may develop. This can also lead to decreased functioning of the thyroid gland.

Iodine deficiency isn’t common in the United States, but is still an issue in parts of Europe, Asia, and Africa.

Lymphadenopathy

When a lymph node becomes enlarged, it can appear under the skin as a nodule. This can be seen commonly when a person has an infection. The swelling should resolve as the infection resolves.

Other causes

Most nodules are benign. However, nodules can be cancerous. If a nodule grows rapidly or persists for a long time, seek a medical evaluation.

Seek immediate medical attention if you experience symptoms such as:

Even if you don’t think your nodule is harmful, it’s best to contact your doctor for an accurate diagnosis.

How are skin nodules diagnosed? | Diagnosis

Your doctor will closely examine your nodule to determine its cause. Sometimes the cause isn’t obvious, and imaging studies, such as an ultrasound, may be needed. An excision is also another way to remove a nodule and find out what the cause of it is.

If the nodule is noncancerous, such as a benign thyroid nodule, your doctor may choose to monitor the nodule without providing treatment.

If the overproduction of a hormone, such as the thyroid hormone, is causing a nodule to form, your doctor may give you prescription medications to suppress the hormone, causing the nodule to shrink.

In some cases, surgery is necessary to remove thyroid nodules. If a nodule is cancerous, your doctor may suggest surgery, radiation therapy, chemotherapy, or all three treatment options to treat the nodule.

The outlook for people with nodules depends on their underlying cause.

If a swollen lymph node that’s present during an infection (such as an upper respiratory infection) is the cause of the nodule, then it will improve with time as the infection resolves. In cases of cancer, early diagnosis is key to effective treatment.

If you do find a nodule, see your doctor to see what the diagnosis could be. Keep track of any other symptoms you’ve experienced, changes in size to the nodule, or any pain associated with the nodule. Share this information with your doctor.