Thyroid Nodules: What They Are and How They Are Detected

A thyroid nodule is a distinct area of tissue that differs in structure from the rest of the gland. Many people hear this wording after an ultrasound: nodules are found in 4% of the US population, and according to autopsy and ultrasound data, in up to half of people worldwide. Let us explain what this formation is and how it is examined.

What thyroid nodules are

The thyroid gland is a small butterfly-shaped gland in the lower front of the neck; its hormones affect almost every organ. A nodule is an abnormal growth of gland cells that forms a lump inside it; in clinical practice this is a neoplasm of any size that may have a capsule and is detected by palpation or visual examination. A solitary nodule, multinodular goiter, and conglomerate goiter are distinguished. Most nodules are benign, but a small proportion contain cancer, so most nodules need evaluation. What to remember: a nodule is not a diagnosis but a finding that needs to be assessed.

Why nodules and small nodules appear

The causes of most nodules are unknown. They are extremely common: by age 60, about half of people have a nodule found on examination or imaging. Hashimoto's thyroiditis, the most common cause of hypothyroidism, is associated with an increased risk; iodine deficiency also causes nodules. Benign formations occur 6–8 times more often in women; malignant ones (5–10% of all cases of nodular goiter) occur equally often in both sexes. What to remember: the appearance of a nodule does not indicate how dangerous it is.

How nodules manifest and whether they can be seen in a photo

Most often nodules cause no symptoms. They are found incidentally—on examination, on a CT or neck ultrasound done for another reason, sometimes because of an altered hormone test. A person may notice a bump in the mirror, when fastening a collar, or when putting on a necklace. Nodules larger than 1 cm are usually detectable by palpation or visible to the eye—these are the ones that appear in a photo of the neck; a nodule inside the gland and its size are determined by ultrasound.

Rarely, pain in the neck, jaw, or ear is troublesome—usually it is associated with rapid enlargement of the nodule, an inflammatory process, or hemorrhage; inflammation of the thyroid gland is called thyroiditis (a separate condition, different from a nodule). A large nodule compressing the windpipe or esophagus causes difficulty breathing and swallowing and a tickling sensation in the throat. What to remember: the absence of symptoms proves nothing.

The nodule itself is not a reason to call an ambulance. Call 103 or 112 if it is hard to breathe due to airway compression.

How a nodule is detected: ultrasound, tests, biopsy

The doctor palpates the gland and assesses whether it is enlarged, whether there is one nodule or several. Among the tests, TSH, T4, and T3 are checked. Ultrasound is the key method: sound waves show whether the nodule is solid or fluid-filled, provide an accurate size and features more often seen in cancer, detect small nodules, and allow them to be monitored over time. In fine-needle aspiration biopsy, cells are taken from several areas of the nodule with a thin needle and examined under a microscope; the procedure is outpatient and fasting is not required. For substernal goiter, an X-ray with barium contrast of the esophagus is done, and scintigraphy shows a "hot" or "cold" nodule. What to remember: the picture is assembled from examination, hormones, ultrasound, and cytology.

What the size of a nodule means

Size is a guide, not a verdict. Nodules larger than 1 cm are usually detectable by palpation or visible to the eye; large nodules sometimes interfere with swallowing, are pressed by clothing, and may compress adjacent organs. It is not customary to name a single threshold for a 2 cm nodule: the exact size and dynamics are shown by ultrasound, which is repeated to see whether the nodule is growing or shrinking. Examination and blood tests usually cannot determine whether there is cancer—this requires ultrasound features and biopsy. What to remember: a large nodule requires attention but does not mean cancer.

Risks and when an endocrinologist consultation is needed

More than 90% of nodules are benign. A single nodule is malignant more often than multiple ones. Nodules may be firm and adherent to surrounding tissues; rapid growth of a nodule is associated with pain; hoarseness is possible if the nodule affects the vocal cord nerve, usually in cancer.

• you have seen or felt a formation on the neck;
• TSH, T4, or T3 levels are altered;
• there is difficulty swallowing, a feeling of compression, or hoarseness;
• the nodule is growing rapidly or the neck, jaw, or ear hurts;
• Hashimoto's thyroiditis has been previously detected.

The scope of examination and further management are determined by the doctor. This material is for reference and does not replace consultation with a specialist.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer