Thyroid Nodules Explained

“I have a nodule in my thyroid gland. What should I do?”

This is a question that I keep getting asked. At the end of the day what we should be asking is “Is this a benign (harmless) lump / nodule or is it thyroid cancer (bad)?”

To try and answer this we need to look at the different types and patterns of thyroid nodules.

The Cheesecake

The thyroid gland is a small butterfly shaped gland that lies in the neck in front of the windpipe.
(For an explanation of what it does see my earlier article “Thyroid Gland Problems”)

If we take a normal thyroid gland and cut it in half the cut surface looks smooth and homogenous, with no nodules present (think of it like a CHEESCAKE)

Some conditions of the thyroid can present like this (eg Grave’s disease) but they are all benign. That is not to say they are without problems and Grave’s disease has to be carefully managed otherwise the person can end up very ill.

Back to nodules….

 The Fruitcake

So your thyroid gland has nodules.
If there are many nodules affecting both sides of the thyroid gland then you are likely to have a condition known as Multinodular Goitre.
If we cut the thyroid gland in half we see many nodules big and small, some white and some filled with jelly like material (think FRUITCAKE)

Multinodular Goitre

Multinodular goitre is a benign degenerative condition of the thyroid gland and left alone they gradually grow in size.
They can get very large and the largest one I have removed weighed nearly 1kg!
Very large multinodular goitres can press on the windpipe (trachea) and cause severe narrowing of the airway and difficulty breathing (see my story “A Visitor From Afar”) It can also press on the gullet (oesophagus) causing discomfort or obstruction to swallowing.
Small multinodular goitres may be observed and monitored with regular scans but large ones should be removed.

and … The Avocado

What if there is only one nodule?
The cut surface of the thyroid gland is smooth like the cheesecake except there is one large nodule in the middle of it (think AVOCADO).

Solitary solid thyroid nodules like this one may be due to thyroid cancer

This is where it gets interesting ..…. because thyroid cancer can present in this way, as a solitary thyroid nodule.
Not all solitary thyroid nodules are cancer – in fact the majority of solitary thyroid nodules I deal with are benign.
However, we do not want to miss cancer because some types of thyroid cancer are very treatable indeed.
With correct treatment patients can go on to live for years and years.

So – it is REALLY important to make sure that solitary nodule is not a bad one.
To do this, we need to learn more about the nodule.
Is it solid (all flesh inside), or is it cystic (fluid inside, like a bubble)?
Or is it half solid half cystic (complex cyst)?

An ultrasound scan is invaluable here.
If the scan shows the nodule to be a simple cyst, that is almost always entirely benign.
The fluid can be aspirated, sucked out with a syringe and the lump goes away or it can be left alone.
However, large cysts (larger than 3cm) should be removed so that we can be sure they are benign and don’t recur.

A solid lump could be cancer especially if the ultrasound scan shows areas of increased blood flow within it.

What about solid/cystic lumps?
Well, they are to be treated with suspicion too because Papillary cancer of the thyroid can present exactly like that – a complex cyst.

Papillary cancer in a thyroid cyst

If you have a multinodular goitre but one of the nodules is much bigger than the rest (dominant nodule in a multinodular goitre), that should be regarded like a solitary solid nodule because we can occasionally find a thyroid cancer developing against a background of multinodular goitre.

Ultrasound scans tell us much about the nodule but it cannot confirm if a lump is benign or cancerous.
To do this we need to look at tissue from the lump. There are 2 ways to do this:

 Fine Needle Aspiration Cytology (FNAC)

A fine hollow needle is passed into the nodule. Suction is then applied with an attached syringe.
The needle is then passed back and forth through the nodule several times.
Cells dislodged by the needle are sucked into the hollow needle then expelled onto a microscope slide and examined.

Fine Needle Aspiration Cytology

An FNAC is quick, cheap and easy. One cancer cell seen is one too many.
However, because the size of the sample is tiny, there is the possibility of sampling error.
In addition, if we see a type of cell called follicular cells we cannot be sure if it is a benign follicular adenoma or a follicular carcinoma (cancer).
A result that shows no cancer cells is of limited use because we wouldn’t know if you are really in the clear or if the needle missed something.
Of course we could repeat the test a few times and hope to increase the accuracy of the test, but we cannot ever be 100% sure.
So, an FNAC is only really useful if it shows one or more cancer cells (bad).
This is a test that is only good if it delivers bad news!

 Thyroid surgery

The other way to look at tissue is to take it out.
With examination of the entire nodule, the likelihood of error or inaccuracy is very, very low.
Of course the obvious downside is that it involves a trip to the operating theatre.
We make the lump go away but exchange it for a scar.
And I will have to have a conversation with you about the potential risks of surgery.
But that is a topic for another article.

So, is your enlarged thyroid gland a cheesecake, fruitcake or an avocado?