What Are Nodules?

A nodule is a lump of tissue that feels like a firm bump. Nodules can form in various places in the body, including in or under the skin and inside organs like the lungs or thyroid.

The term "nodule" is generally used as a descriptor to identify these growths. It is not a diagnostic term and refers more to the lump's appearance than its cause.

Nodules can form just about anywhere. Some are deep inside the body and may only be detected through imaging tests, while others, like those under the skin, are more noticeable.

Common sites where nodules form include the thyroid, lymph nodes, and lungs, but they can also appear in the neck, vocal cords, throat, groin, and armpits.

Nodules under the skin can be easy to detect and often feel like hard, round bumps.

They may not be painful or cause other symptoms, and many go unnoticed unless they begin to grow and press on nearby tissue. At that point, they may start to cause pain.

Thyroid nodules are solid or fluid-filled lumps that form in the thyroid, located just above the breastbone at the base of the neck. Many people with thyroid nodules do not realize they have them.

Doctors may discover them during routine exams or while performing scans for another reason. However, some thyroid nodules may become large enough to be visible or press on the esophagus or windpipe, causing issues with swallowing or talking.

In some cases, thyroid nodules can produce excess thyroxine, a hormone secreted by the thyroid gland, which causes symptoms like tremors, weight loss, sweating, nervousness, or an irregular heartbeat.

Most thyroid nodules are not cancerous, but there is no way to tell whether one is benign without testing.

Cancerous thyroid nodules are generally slow-growing, and many thyroid cancers are curable.

Lung nodules are common and can result from a number of causes, including inflammatory conditions, infections, inhaled particles, and cancer. Most people are unaware of lung nodules. They are often found during chest X-rays or scans done for other reasons.

Small lung nodules rarely cause symptoms. However, if they grow or become cancerous, people may experience shortness of breath, chest pain, hoarseness, a chronic bloody cough, or recurring respiratory infections.

Other concerning symptoms can include fatigue, loss of appetite, or unexplained weight loss.

Most lung nodules are not cancerous. Nodules that are small and do not grow are unlikely to become cancerous, but they may require monitoring to ensure they do not change.

When a nodule is large or growing, additional testing may be needed, such as a biopsy, CT scan, or PET scan.

Nodules can form on the vocal cords from overuse. The vocal cords are folded membranes, and with overuse, the tissue can swell, leading to nodule formation. They usually make the voice sound hoarse, raspy, or breathy.

These nodules can also affect a person's singing voice, making it difficult to hit high or low notes or hold a note as long as usual.

Vocal cord nodules are non-cancerous, and most go away on their own with rest or voice therapy. They do not usually cause serious problems, though surgery may be needed if they don’t resolve on their own.

Lymph nodes are located throughout the body and are a key part of the lymphatic system, which defends against cancer and infection. Their job is to filter cancer cells, damaged cells, and infectious organisms and destroy them. If a large number of these cells are present in a node, it can swell.

Swollen lymph nodes are sometimes referred to as nodules. They may be painful and show signs of infection, appearing in one or several areas of the body. Upper respiratory infections are the most common cause. Only about 1% of swollen lymph nodes are cancerous.

Most lymph node nodules resolve on their own, but some features should be monitored. A doctor should examine nodules an inch or more in diameter, draining pus or fluid, firm to the touch, or accompanied by fever or unexplained weight loss.

Widespread swelling that doesn’t go away after four weeks should also be evaluated. Blood tests or biopsies may help determine the cause.

Nodules can result from inflammation, injury, infection, hormone imbalances, iodine deficiency, or autoimmune conditions.

While most are benign, testing may be needed to rule out more serious causes. Accurate diagnosis ensures proper care and peace of mind.

No, most nodules are benign—especially small ones that grow slowly and do not cause symptoms. Cancer is a possible cause, but it’s relatively rare.

For example, lung nodules are found in about 30% of chest CT scans in the U.S. each year, but the probability of cancer is less than 1% for nodules smaller than 6 mm and only 1–2% for those between 6–8 mm. However, large or fast-growing nodules should always be evaluated by a doctor.

If a nodule is growing, changing, or causing other symptoms, medical attention is warranted. Concerning signs like difficulty breathing, chest pain, or coughing up blood require immediate care.

While many nodules resolve on their own, those lasting more than three to four weeks—especially without other symptoms—should still be checked by a doctor.