Non-Thyroid Neck Masses: The Common - The Classics - The Mimics - HD

Introduction and Objectives

We've reached the final half hour of the Head and Neck SAM session and while it may be hard to believe that one could add much more to the topic than what our previous excellent speakers have already taught us, I am gonna try to round things out a little bit, even build on some of what we've learned so far.

And I'm gonna review with you some non thyroid, non salivary gland neck masses that you're likely to encounter in your practice.

I wanna thank the program committee for the invitation and special thanks to Carl Redding and Bill Charnow for their input on this talk.

I have no disclosures.

Our objectives for the next hopefully about 20 minutes, are to understand the ultrasound appearance of common and recognizable masses in the neck using a case-based approach and correlation to CT and MR as well as pathology.

We will also briefly discuss at the end some entities that may mimic a neck mass, either on physical exam or on imaging.

Now this can be a confusing topic and one reason for that is that there are so many different ways to organize it.

The topic of non thyroid neck masses can feel like sort of a hodgepodge of barely related entities linked together only because they can all occur in the neck.

It's also challenging to feel a mastery of this topic.

If you like me, don't spend any time in a neuroradiology reading room.

Ultrasound remains very central to the evaluation of palpable and non palpable neck masses, and I'm hoping to remind you of that today.

Although categorizations based on age, location, morphology and etiology are all very valid and very useful, I'm gonna propose another way to think about these and that is by the following three questions for us.

As radiologists, what will I see in my practice?

What can I pretty much always confidently diagnose and what has the potential to fool me?

So I call these the common, the classic, and the mimics.

So when I say common, I mean things that are must know entities because not only are they relatively common in practice, by no means obscure, they're also commonly taught and commonly inquired about by our referring clinicians.

These are of course the brachial cleft cyst, cervical lymphadenopathy and thyroglossal duct cysts.

The classics are entities that are really Aunt Minis.

The imaging appearance is predictable and usually diagnostic.

These are carotid body tumors, lipomas, epidermoid cysts and neurogenic tumors and the mimics, well, those are just that potential mimics or pitfalls or things that could cause confusion if you don't consider them diagnostic possibilities.

The thyroid pyramidal lobe, carotid artery aneurysms, jugular vein thrombosis, and even the terminal portion of the thoracic duct.

So seven diagnoses are here that I really want you to feel like you own.

At the end of this talk, we will not be covering of course, thyroid, parathyroid, salivary glands.

Those have been well covered in previous talks, I'm not gonna address infection granulomatous disease or a comprehensive pediatric differential diagnosis either.

But let's get started.

Common Neck Masses

Second Branchial Cleft Cyst

When a patient presents with a cystic mass in the lateral neck, this is most typically a second brachial cleft cyst.

Because the mass is congenital, most patients present between the ages of 10 and 40, they may complain of a slowly enlarging painless lateral neck mass.

These are smoothly marginated and less infected.

Second brachial cleft cysts are located in a predictable spot along the anterior border of the sternocleidomastoid muscle, usually near just below the angle of the mandible.

That is because the embryologic structure from which these arise.

The second brachial cleft extends from the tonsillar fossa to the anterior border of the sternocleidomastoid.

Mastoid transverse and longitudinal ultrasound images here, as well as axial CT image from a contrast enhanced CT show a smoothly marginated cystic mass, which pushes the SCM posterolaterally, the carotid posteromedially and the submandibular gland anterolaterally.

Treatment is surgical because of the risk for infection and I show here the surgical specimen showing the cystic nature of the resected second brachial cleft cyst.

Although first, third, and fourth cleft cyst can occur, they're uncommon, very uncommon and rare respectively.

The second brachial cleft cysts account for 70 to 90% of cleft anomalies.

The anatomic illustration here again shows the typical location of this lesion.

Here are two more examples to review the imaging appearance and the anatomy of the branchial cleft cyst.

This is a 24-year-old patient who presented with a right second brachial cleft cyst, which we see on CT again at that typical location causing the same type of mass effect we just described.

This second case on ultrasound was a 44-year-old who presented with a left cystic lateral neck mass, which was a second brachial cleft cyst.

Here's that corresponding intraoperative photo showing the typical location in the lateral neck near the angle of the mandible, superficial to the vessels.

So those were the brachial cleft cysts.

Cervical Lymphadenopathy

Let's move on to lymphadenopathy.

We've learned a lot about lymph nodes already today.

I'm not gonna re-review the cervical lymph node levels nor spend significant time on lymph node metastasis in the setting of thyroid cancer.

Suffice it to say abnormal lymph nodes are commonly the cause of a non thyroid neck mass and can be from a multitude of sources.

I show here three cases of cervical lymphadenopathy, which presented as palpable neck masses on ultrasound.

These nodes are abnormal by size, by shape, and by echogenicity.

They're large, solid and rounded.

The case of lymphoma is the most homogenously hypoechoic, which is typical while the esophageal and lung cancer metastases are more heterogeneous, all showed corresponding hypermetabolism on pet.

But after seeing these sort of run of the mill solid lymph nodes, I want to tell you that one of the most important things that I need to get across, which I'm sure you're all familiar with, but bears repeating, is that metastatic lymph nodes in the setting of head and neck squamous cell carcinoma can be cystic.

These patients may present with an enlarging cystic neck mass as this 50-year-old male did.

Now the ultrasound appearance here is much more heterogeneous than the brachial cleft cyst we saw earlier.

Here. There are internal solid components, but the CT is nearly identical to the earlier cases of congenital brachial cleft cyst, a cystic mass in the lateral neck.

This is anterior to the sternocleidomastoid.

The age of the patient of course, should raise suspicion for malignancy, but we're also seeing these more often in younger patients due to the increase in human papillomavirus associated oropharyngeal cancers.

In this case, pet revealed the primary left tonsillar tumor markedly hypermetabolic and also showed peripheral hypermetabolism in the cystic lymph node.

Cervical nodal involvement is the single most important prognostic indicator for patients with head and neck squamous cell carcinoma.

The nodes we see in HPV positive oropharyngeal cancers may be cystic.

These patients are often younger, have high rates of nodal metastases, but thankfully overall a better prognosis still we have to be vigilant with a new cystic mass in the lateral neck and consider the possibility of a squamous cell carcinoma metastasis even if the appearance is suggestive of a brachial cleft cysts.

Again, this is because HPV associated head and neck cancers are seen in a younger population without traditional risk factors in whom congenital lesions are also high on the differential.

Here's another illustrative example.

A 53-year-old male who presented with a slowly enlarging painless lateral neck mass.

It appeared purely cystic by ultrasound CT and was at the typical location of a brachial cleft cyst.

You can see it is along the anterior border of the sternocleidomastoid muscle below the angle of the mandible and pushing the carotid medially.

This was resected as a presumed second brachial cleft cyst and everyone assumed that that was that, but the pathology came back as metastatic squamous cell carcinoma.

This is not so unusual a story, I'm sure you've heard it or seen it yourself.

Further evaluation revealed a left base of tongue primary and this was resected and he underwent a cervical lymph node dissection.

Another example of a potential cystic mass in the lateral neck.

An older but great case here.

It was metastatic papillary thyroid cancer.

We've seen examples in a previous lecture today as well, but also keeping in mind when evaluating a cystic mass in the neck, this of course had solid eccentric components with internal flow and punctate echogenic foci suggestive of metastatic papillary thyroid cancer.

So again, here are three cases of cystic lateral neck masses, each of which you've learned about so far today.

Brachial cleft cyst, metastatic squamous cell carcinoma, and metastatic papillary thyroid cancer.

I think one point to keep in mind that's helpful is that while brachial cleft cysts and squamous cell carcinoma both tend to occur at level two metastatic papillary thyroid cancer as we learned earlier, is first seen lower in the neck at levels three or four and that can be helpful to tip you off to also look at the thyroid gland in those cases.

So we've covered brachial cleft cysts and lymphadenopathy.

Thyroglossal Duct Cysts

A thyroglossal duct cyst also falls into the common must know category of neck masses.

A patient with a thyroglossal duct cyst will present with a cystic mass in the neck at midline or just off of midline.

These usually present before 30 years of age as they are congenital.

They comprise about 70% of congenital neck masses and conform anywhere along the embryologic route of descent of the thyroid.

From the base of the tongue to the thyroid isthmus, two thirds of thyroglossal duct cysts lie below the level of the hyoid and the remainder are at or above the hyoid bone.

These images show the typical ultrasound appearance with an oval cystic mass at midline.

These tend to be embedded within the anterior strap muscles of the neck and we can see that better here on CT and we can also appreciate it on this clip, which is going from superior to inferior from the hyoid bone to the thyroid.

Thyroglossal duct cysts can contain internal echoes, whether they're infected or not and because they may contain thyroid tissue.

As you know, there's a small risk of developing papillary thyroid cancer within a thyroglossal duct cyst.

The cysts are treated surgically, which requires total cyst excision as well as removal of the central portion of the hyoid bone and the tract to the tongue base.

Otherwise there's a higher risk of recurrence.

Another case here with both ultrasound and CT shows a paramedian location of an infrahyoid thyroglossal duct cyst and the way that these are embedded within the strap muscles of the anterior neck.

One trick you can use to confirm the diagnosis is to image with the ultrasound during tongue protrusion because the tract from which these cysts arise extends into the base of the tongue, the cysts typically move superiorly with tongue protrusion.

You will see them slide superiorly along with the other deep structures and distinct from the superficial tissue.

A few variants that are worth seeing.

An infected thyroglossal duct cyst on the left showing a very thickened irregular wall thickened inflamed surrounding tissue, an internal debris within the cyst and on the right soft tissue nodularity within the cyst with internal flow and post contrast enhancement on ct.

And that was a papillary thyroid cancer.

Occasionally a thyroglossal duct cyst will develop a fistula to the skin typically after infection, as was the case for this pediatric patient who underwent subsequent resection.

So now we've covered some of the common must know non thyroid neck masses.

Classic Neck Masses

Let's move to the classics.

Those recognizable Aunt Minis that have a classic ultrasound appearance.

Carotid Body Tumors

A patient with a carotid body tumor will typically present with a palpable lateral neck mass that is solid.

These are located at the notch of the carotid bifurcation splaying the internal and external carotid arteries.

This is where the carotid body lies.

That of course being a cluster of glomus cells, the peripheral chemoreceptors from which these tumors arise, they are highly vascular masses, typically with detectable internal flow on color doppler imaging.

The MR images here confirm that location at the carotid bifurcation splaying the internal and external carotid arteries and the signal intensity shows the typical T1 hyperintense T2 hyperintense with sort of salt and pepper appearance indicating internal hemorrhage and internal flow.

Carotid body tumors enhance robustly after contrast administration, as you can see on the CT case with another typical ultrasound companion image.

These are part of the wider category of glomus tumors that we call paragangliomas.

The carotid body tumor is the most common paraganglioma of the head and neck with tumors at the jugular bulb in the middle ear and along the vagus nerve being less common.

These are treated surgically as they do have a risk of becoming locally invasive or even metastasizing carotid body tumors can be bilateral and 10 to 30% of patients.

And here's a nice example of bilateral carotid body tumors.

Let's move on to lipoma.

Lipomas

Although lipomas can occur anywhere in the body, they are common in the neck and a patient may present to ultrasound with a palpable neck mass.

Their provider may suspect a lipoma based on physical exam findings of a soft or rubbery mobile mass similar to this photo, but ultrasound is sometimes pursued to exclude more sinister things like lymphadenopathy.

That was the case in this 38-year-old female who presented with a palpable posterior neck mass.

One interesting thing about lipomas is that it's often the larger ones that are harder to see clearly and to define when imaging with ultrasound.

This one does however, have a typical appearance of a mass in the subcutaneous tissue that is isoechoic to surrounding fat is wider than tall and has thin wavy internal echogenic lines and no detectable internal color flow.

This was also imaged with mr and you can see on T1 weighted sequence it is isointense to the surrounding fat.

These can be stealthy though the larger they are.

This is the same patient that large posterior cervical lipoma on a clip almost blending into the background tissue.

While most often isoechoic to surrounding fat lipomas may also be hyper or hypoechoic.

They should be smooth shown, no posterior acoustic shadowing and be wider than tall.

The wavy internal echogenic lines are typical and lipomas should also be compressible as in the case shown here.

Again, a smaller lipoma such as this is often easier to see than the larger ones, but they really do all have a classic appearance.

Epidermoid Cysts

Another mass with a classic ultrasound appearance is the epidermoid cysts.

The typical history is of a slowly growing non-painful firm, superficial nodule, usually small.

These are hypoechoic ovoid or spherical nodules with multiple internal echoes and increased through transmission as seen.

Here they show no internal color flow on color doppler because they're filled with avascular squamous debris and keratin.

This one was sampled and only a small amount of thick white fluid was obtained.

Epidermoid cysts arise due to a proliferation or progressive collection of epidermal tissue within the dermis.

If they rupture, there can be a local inflammatory response that mimics infection.

You may be able to show dermal extension with ultrasound, but if not, at least contact along the dermis.

Another example of an epidermoid cyst here, this one came as a suspected thyroid nodule and you can see exactly why it's right at the level of the thyroid gland.

However, on imaging this was anterior to the strap muscles, not in the thyroid at all, and it contacted the dermis.

This was an epidermoid cyst.

Neurogenic Tumors

Neurogenic tumors are another neck mass with a classic imaging appearance.

Let's take a look here.

This was a 59-year-old female who presented with a firm mass in the right supraclavicular fossa, an ultrasound.

It was actually initially thought to be an abnormal lymph node.

It's hypoechoic and rounded, but had we looked a little closer, we may have appreciated a somewhat fusiform morphology and tapering at the edges with continuity to hypoechoic linear tubular structure, which was better appreciated on the cine clip that was taken when she came for a biopsy, the FNA was attempted, but as you can guess, she didn't tolerate it very well and that's pretty typical when we try to sample a neurogenic tumor.

She actually went on to MRI and on coronal T1 pre and post contrast images, we see an enhancing solid mass to correspond to the ultrasound finding with a tail of enhancement.

That, of course, was the nerve.

This was resected and found to be a schwannoma.

The intraoperative picture shows that red surgical tie right around the nerve from which this mass was arising.

Neurogenic tumors such as schwannomas or neurofibromas are typically solid homogenous and hypoechoic with posterior acoustic enhancement.

They classically show a tail or dumbbell configuration and an ultrasound we can certainly try to evaluate for continuity with a peripheral nerve.

So we've looked at the common and the classic non thyroid neck masses in the last few minutes.

Mimics of Neck Masses

Let's discuss and take a look at some of the mimics.

The thyroid pyramidal lobe is common and the more you look for it, the more you'll see it.

This was sort of an interesting case of a 60-year-old male who had a history of papillary thyroid cancer.

He had a total thyroidectomy in 2011 and he presented just this summer with a new palpable nodule in the mid neck.

So we see here a mixed solid and cystic nodule measuring about a centimeter, which took a little closer look and if you can see here, it seems to be in continuity with a column of hypoechoic soft tissue extending caudally toward the thyroidectomy bed.

We look back to see an old CT that he had had prior to his thyroidectomy and indeed you can see enhancing tissue looks similar to his thyroid gland on this old CT scan that was arising at midline extending cranially from the thyroid.

This clip goes a little fast, but again you can see here that was a pyramidal lobe of his thyroid gland five, six years prior.

So this was a new palpable nodule and what we presumed was a retained pyramidal lobe of the thyroid.

This went for surgical resection and was benign pyramidal lobe with findings of chronic thyroiditis and a benign thyroid nodule.

The thyroid pyramidal lobe is found in about 50 to 80% of patients, although in some it's very small, but any diffuse process of the thyroid may involve the pyramidal lobe.

Here's an older case that shows scanning from superior to inferior, a cystic nodule in a pyramidal lobe, similar to some of the cystic nodules you see in the thyroid lobe itself toward the end of the clip.

So again, a process that affects the thyroid gland will affect the pyramidal lobe itself.

So don't be confused.

What about this case?

What else do we need to keep in mind when we're looking at possibly a cystic lateral neck mass?

We need to ask ourselves, is it a vessel internal carotid artery aneurysms?

I've seen come in with non-diagnostic FNAs at the outside for complaint of neck mass, so just keep it in mind.

Similarly, once in a while, something palpable in the lower neck may also be vascular like an internal jugular vein thrombosis rather than adenopathy.

Typically, this has worked out clinically, but once in a while, this is what corresponds to a palpable finding in the neck.

One of the more interesting cases I wanna show you as a mimic is this and a companion case.

Next.

This was a case I saw not too long ago, and this was incidental.

The patient's neck was being scanned to evaluate the thyroid, which was negative, but the sonographer came in and we were looking at this area.

We scanned a little bit, and this was maybe a lymph node.

It was very close to the jugular vein, but we couldn't get over the fact that it seemed to be tapering toward that jugular vein right at the most inferior aspect, almost like it was communicating to it.

It wasn't a vessel itself.

This of course, turns out to be the terminal portion of the thoracic duct, a little bit prominent in this patient.

Here's a clip in a separate patient on the right side where you can also see a terminal portion of a thoracic duct with more clear communication to the jugular vein where it has its confluence with the subclavian.

I'm gonna play that again,

So this can be a little bit of a pitfall, but the lower body in the GI tract, lymphatic drainage goes into the cervical veins right at this location most of the time on the left, some of the time bilaterally, occasionally just on the right.

The thoracic duct typically enters the lateral internal jugular vein at its junction.

With the subclavian, it's usually only about two or three millimeters in diameter.

We usually don't appreciate it, but it can be larger if a patient has a history of cirrhosis or congestive heart failure or some other volume overload issue.

Venous reflux can also occur into a dilated duct and cause it to become more and more dilated.

This actually became symptomatic and this went to a resection.

Conclusion

So overall, I hope you've gotten appreciation for some of the common non thyroid, non salivary gland masses, some of the masses that have a classic or Aunt Minis imaging appearance and some of the potential mimics that you might see.

We talked about brachial cleft cysts, lymphadenopathy, thyroglossal duct cysts.

We looked at carotid body tumors, lipomas, epidermoid cysts, and neurogenic tumors, and some of those potential mimics that we went over briefly at the end.

I want to thank you so much for your attention.