Short answer: Most thyroid nodules are not cancer, and many only need watching with a repeat ultrasound. The decision rests on three things: your TSH blood test, the ultrasound appearance (scored as TIRADS) and the size of the nodule. A needle test (FNAC) is advised only when the score and size call for it, and a surgeon's opinion is sought when the needle test, the size or your symptoms make surgery a reasonable choice.

If you have been told you have a thyroid nodule, you are not alone. Nodules are very common and are often found by chance on a scan done for another reason. The question that matters is not "is there a nodule?" but "what, if anything, should be done about it?". This post explains how that decision is usually made. For a fuller background, read a thyroid nodule was found: what happens next?.

Is my thyroid nodule likely to be cancer?

Usually not. Careful studies show that only a small minority of thyroid nodules are cancer. Even when a nodule does turn out to be cancer, most thyroid cancers grow slowly and have a very good outlook with treatment.

Besides cancer risk, doctors look at two other questions:

  • Is the nodule making too much thyroid hormone? A "hot" nodule can cause an overactive thyroid. These nodules are rarely cancer.
  • Is it big enough to cause symptoms? A large nodule or goitre can cause a visible swelling or pressure on the windpipe or food pipe.

What does the ultrasound (TIRADS) tell us?

The first test is usually a TSH blood test. If TSH is low, the nodule may be overactive and a thyroid scan may be more useful than a needle test. If TSH is normal or high, the next step is a good quality ultrasound of the neck.

On ultrasound, the nodule is described by what it is made of (fluid or solid), how dark it looks, its shape, its edges and whether it has tiny bright spots. These features are combined into a TIRADS score, from very low to high suspicion. Indian reports may use the American (ACR TI-RADS) or the European (EU-TIRADS) version.

The score is only half of the picture. The size of the nodule is the other half. The ultrasound also checks the lymph nodes in the neck.

When is FNAC needed?

FNAC (fine-needle aspiration cytology) uses a thin needle, usually guided by ultrasound, to collect a few cells from the nodule. It feels similar to a blood test and takes only a few minutes.

FNAC is usually advised when:

  • the nodule has a moderate or high suspicion score and has reached the size threshold for that score;
  • the ultrasound shows suspicious lymph nodes in the neck;
  • there are other risk factors, such as a strong family history of thyroid cancer or radiation to the neck in childhood.

FNAC is usually not needed for nodules that look benign or very low risk on ultrasound, or for small nodules below the size threshold for their score. These nodules are usually watched instead.

The cells are reported using the Bethesda system, which places the result in one of six categories, from benign to malignant. The result guides the next step: follow-up, a repeat test, or a surgical opinion.

When is a surgeon's opinion needed?

An experienced thyroid surgeon is an important partner in nodule care. A surgical opinion is usually sought when:

  • the FNAC result is suspicious for cancer or shows cancer;
  • the result is indeterminate and a repeat test or other options have not settled the question;
  • a nodule or goitre is large enough to cause pressure symptoms, difficulty swallowing or breathing, or a visible swelling that bothers you;
  • surgery is a suitable treatment for an overactive nodule in your situation.

The endocrinologist and the surgeon work together, and the final choice is made with you after discussing the benefits and risks. In some centres, non-surgical options such as radiofrequency ablation are available for selected benign nodules.

What does follow-up look like?

If your nodule is benign or low risk, follow-up usually means a repeat ultrasound after an interval your doctor will advise, and less often once the nodule has stayed stable. A small increase in size is common and is not, by itself, a sign of cancer. Your doctor will tell you which changes would prompt a repeat FNAC.

Thyroid hormone tablets are no longer routinely used to shrink benign nodules.

When to see a doctor urgently

Seek urgent care if you have: sudden painful swelling in the neck, difficulty breathing or noisy breathing, difficulty swallowing even liquids, or a new hoarse voice that is getting worse quickly. If breathing is affected, go to the nearest emergency department immediately, or call 108 or 112.

Read more

Book a consultation with Dr. Om J Lakhani at AB Plus Hospital, Ahmedabad, or online → consult.dromlakhani.com. Call +91 73738 48848 for appointments.

References

  1. Haugen BR, et al. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid. 2016. PubMed
  2. Tessler FN, et al. ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of the ACR TI-RADS Committee. J Am Coll Radiol. 2017. PubMed
  3. Ali SZ, et al. The 2023 Bethesda System for Reporting Thyroid Cytopathology. Thyroid. 2023. PubMed
  4. Durante C, et al. The Diagnosis and Management of Thyroid Nodules: A Review. JAMA. 2018. PubMed