Thyroid nodules are extremely common! If I pulled 1000 people randomly off the street and did an ultrasound of the thyroid, I could find anywhere from 300-600 nodules!
Overwhelmingly, thyroid nodules are BENIGN.
When they are not benign, the malignant ones are overwhelmingly Papillary type, which by nature is very slow growing. It can take many years for it to actually cause significant harm:
- There are a few exceptions to this, like with unusual variants of papillary cancer, or a different type of thyroid cancer that is rare.
What Do We Do About Thyroid Nodules?
- First we check if the thyroid hormones are affected at all.
- If the thyroid is overactive, it is exceedingly rare for a nodule to be malignant. In that case we treat the hyperthyroidism.
- If the thyroid hormones are NORMAL, we need an ultrasound to tell us more about the nodule. The nodule is given a TIRADS score based on size and certain characteristics.
TIRADS Score and Cancer Risks
- TIRADS 0 → NO malignant potential
- TIRADS 1 → Normal thyroid
- TIRADS 2 → 0.9% risk of cancer; biopsy if > 2.5cm
- TIRADS 3 → 2.9% risk of cancer; biopsy if > 2cm
- TIRADS 4 → 38.1% risk of cancer; biopsy if > 1.5cm
- TIRADS 5 → 86% risk of cancer; biopsy if > 1cm
Biopsy Procedure
If a nodule meets criteria for biopsy, it is done with a thin needle and lidocaine anesthetic, with an ultrasound to guide the biopsy:
- There will be 4 passes through the nodule, with 1 being reserved in Veracyte solution as a “backup plan.”
- Veracyte can be sent for genetic testing, depending on what the pathologist says about the biopsy.
Biopsy Results (Bethesda Cytopathology for Thyroid)
Inadequate/Non-diagnostic Specimen
- 5-10% risk of cancer
- The sample did not have enough cells to make a diagnosis; this will require a repeat biopsy, sometimes 3 months down the road.
Benign
- 0-3% risk of cancer
- We follow it with ultrasound over the course of years. It will probably grow, and that’s OK. But if it starts to look “different” then we would consider a new biopsy.
Atypia of Uncertain Significance
- 6-30% risk of cancer
- The cells look “funny” but it’s hard to tell if it’s actually a bad thing. This is a time we will use the veracyte solution to check genetic markers on the sample.
Suspicious for Malignancy
- 45-60% risk of cancer
- Depending on exactly what the pathologist said about that nodule, we may proceed to surgery to remove either the whole thyroid, or the part of the thyroid with the nodule in it.
Malignant
- 94-99% risk of cancer
- The standard of care is to remove the whole thyroid.
Resources
- American Thyroid Association: https://www.thyroid.org/thyroid-nodules/
- Mayo Clinic: www.mayoclinic.com