Core Needle Biopsy of the Salivary Glands - HD

Introduction

Hello, I'm Jason Wagner from the University of Oklahoma.

This talk discusses needle biopsy of the salivary glands with emphasis on core biopsy.

I have no financial disclosures relevant to this talk.

Patient Case

Going to begin by discussing a real patient case that I've seen within the last year.

This was a 65-year-old male with newly diagnosed right supraglottic laryngeal squamous cell carcinoma, who presented also with necrotic metastatic right neck adenopathy.

But on his pretreatment evaluation, he was also found to have a lesion in the contralateral or left parotid gland that you can see here, a solid hypoechoic lesion that was fairly hypervascular and on a PET CT was hypermetabolic.

The patient was referred for a needle biopsy, and we began with a fine needle aspiration of this lesion.

The preliminary cytopathology was lymphocytes and atypical squamous cells with a pathologic differential diagnosis of Warthin's tumor with squamous features versus a lymph node with metastatic squamous cell carcinoma.

Unfortunately, that is a very unhelpful differential diagnosis, because the two different possible diagnoses would have very different treatment implications.

The Warthin's tumor would just be watched and metastatic disease to the contralateral parotid gland would substantially change the patient's radiation therapy plan.

So it's important to distinguish between the two.

So what are the possible options that we could do in this case?

Here are four possible options that could be considered.

Perform a core biopsy, bring the patient back on another day to repeat aspiration biopsy.

Recommend a surgical excisional biopsy, or recommend just treating as a presumed metastasis.

We will get back to this case a little bit later in the talk, but here's the basic outline of the talk.

Talk Outline

A brief description of anatomy and pathology of the salivary glands, primarily the parotid gland.

And then discussing the pluses and minuses of fine needle aspiration versus core biopsy of salivary masses.

And finally, the discussion of biopsy technique.

Anatomy of the Parotid Gland

Very briefly, the anatomy of the parotid gland has some significant implications when discussing and considering needle biopsy.

The major one is the facial nerve and its branches, which divide the parotid gland into superficial and deep lobes.

We usually cannot see the facial nerve, but we can usually see the retromandibular vein, which is an imaging marker for the facial nerve.

And in about 65% of people, the facial nerve lies just lateral or just superficial to the retromandibular vein.

There are distal branches of the external carotid artery within the parotid gland, and the distal internal carotid artery is near the deep margin of the parotid gland.

The parotid gland contains lymph nodes, which are commonly seen on diagnostic ultrasound, and is the reason why it is common to see lymphoma and metastatic disease in the parotid glands.

Here's an example of a hypoechoic large mass in the parotid gland that may look relatively superficial.

There doesn't appear to be much parotid tissue overlying this big mass.

So here is the mass, here's the parotid tissue, here's the overlying subcutaneous tissue.

However, when we interrogated it more, we found this vessel, which is the retromandibular vein to be displaced superficially by the mass, and therefore, this mass is in the deep lobe.

I said that we usually cannot see the facial nerve in its branches, which is true.

However, in this unfortunate case, we actually could see many of the branches of the nerves.

These hypoechoic branching structures that can be seen within the parotid gland are the nerves that are visible because this unfortunate man had extensive perineural spread of squamous cell carcinoma, allowing us to see the nerves.

And this just gives you an idea of the location distribution of some of the facial nerve branches within the parotid gland.

Pathology of Salivary Glands

What about pathology of the salivary glands?

About 70% of things that clinically present as a parotid mass are actually neoplasms.

The risk of malignancy of a salivary neoplasm is inversely proportional to the size of the gland.

With about 20 to 25% of parotid neoplasms being malignant, about half of submandibular gland neoplasms are malignant, and about three fourths of the rare sublingual gland neoplasms are malignant.

That being said, 70% of salivary malignancies arise in the parotid gland because parotid tumors are far more common than tumors in the submandibular or sublingual glands.

80 to 90% of parotid neoplasms arise in the superficial lobe of the parotid with about 10 to 20 in the deep lobe and a very small number in the accessory lobe.

The accessory lobe of the parotid is located anteriorly along the parotid duct near the masseter muscle.

This is where it gets complicated.

According to the WHO classification, there are 28 different histologic types of salivary malignancy, and many of those have low, intermediate and high grade variants, and that doesn't even include all of the benign things that can occur in the salivary glands.

So the pathology differential diagnosis is very complicated, which raises a question, why do we biopsy salivary gland masses?

Specifically, why do we needle biopsy these?

Why don't we just cut them all out?

It's an excellent question.

And it has been addressed in the literature.

There are several answers to that question.

First of all, some masses are not treated surgically, such as Warthin's tumors, lymphoma, malignancies that are not resectable, non neoplastic lesions and some metastases.

There also are benign lesions such as pleomorphic adenoma, which are often treated surgically due to a risk of malignant degeneration, even if surgical excision is planned.

Preoperative diagnosis is helpful because it allows for appropriate timing and planning of the operative approach, as of course, part of the complete patient workup, and it allows more accurate counseling of the patient regarding their prognosis and the likelihood of facial nerve injury or sacrifice during the surgery.

Surgical incisional biopsy was previously a commonplace procedure maybe a generation ago, but is really fallen out of favor and is considered contraindicated due to the risk of nerve injury and the high rate of tumor seeding.

Therefore, fine needle aspiration of salivary masses has been performed extensively for a number of years, but it is limited by a fairly high non-diagnostic rate and a suboptimal sensitivity for detection of malignancy.

Fine Needle Aspiration (FNA) Limitations

A large study published in 2007 that included both ultrasound guided and palpation guided fine needle aspiration of salivary lesions found a 50% non-diagnostic rate and only a 64% sensitivity for malignancy.

A subsequent study that only included ultrasound guided fine needle aspirations with subsequent excision found a 12% non-diagnostic rate and a 76% sensitivity for malignancy.

However, only 60% of the malignancies were actually diagnosed with FNA.

A subsequent meta-analysis of over 5,600 patients who had FNA of a salivary neoplasm found a 20% overall non-diagnostic rate and a fairly decent sensitivity for malignancy.

But noted there was considerable heterogeneity among studies and among institutions, and there have been multiple other studies looking at fine needle aspiration with fairly similar results.

A few specific topics that can be considered about the results of fine needle aspiration were addressed in these two studies.

In 2014, this study looked at the significance of indeterminate results.

It looked at 317 parotid tumors that were diagnosed or biopsied with FNA, and then subsequently had resection of all of the lesions as expected.

There was a 18% malignancy rate, 82% benign.

However, of the 36% of the lesions that had indeterminate fine needle aspiration results, actually 31% were malignant.

So an indeterminate result of a parotid lesion fine needle aspiration is not a reassuring finding, at least in this study.

Another study in 2010 looked at the utility of repeating fine needle aspiration after a an indeterminate or non-diagnostic result initially.

And of these 135 salivary tumors, the initial FNA was only diagnostic 76% of the time was 70% sensitivity.

However, a repeat FNA was diagnostic 82% of the time with 84% sensitivity for malignancy so that there may be some benefit to repeating a fine needle aspiration.

Returning to the Patient Case

So, returning to our patient case that we began with, in this case, I chose to do a core biopsy at the time of the initial fine aspiration, and it indicated a Warthin's tumor with no evidence of malignancy, and therefore the patient was treated with chemotherapy and standard radiation therapy just to the primary tumor and the nodal bed that was known to be involved with metastatic disease.

Just as a counterpoint though, this is an 85 year old patient who had the main differential diagnosis we were discussing with this case.

This is actually an intraparotid lymph node that has metastatic squamous cell carcinoma within it, and it, although it's a little bit more heterogeneous than this, it looks fairly similar.

And this biopsy was also a core biopsy that confirmed the diagnosis.

Core Needle Biopsy of Parotid Lesions

So what about core needle biopsy of parotid lesions?

One of the initial reports of this was in 2005 with 37 patients.

A subsequent report was in 2007 in a JOR with 135 patients showing extremely good results.

An initial meta-analysis in 2011 of 277 patients yielded a very low non-diagnostic rate and a very high sensitivity for malignancy.

Subsequent meta-analysis also showed a very high rate or high sensitivity and specificity for malignancy with a very low rate of complications and no major complications.

There have been three studies that have directly compared fine needle aspiration and core biopsy of salivary lesions, and you can see that these show a higher non-diagnostic rate and a lower sensitivity for malignancy as compared with the core biopsy arms of the study.

Complications of Core Needle Biopsy

What about complications, nerve injury? Is it possible?

Well, in my opinion, it is possible.

However, it is likely very rare with ultrasound guidance in modern techniques.

None of the articles that I have described in this talk thus far reported any cases of nerve injury.

Temporary weakness of the facial nerve, however, due to lidocaine administration does certainly occur during these biopsies if you place lidocaine within the gland.

What about tumor seeding from the needle track?

Well, this is actually the major complication that most of the literature has focused on.

It has been reported with 14 gauge core.

It has not yet been reported with an 18 gauge core, which does not mean it can't happen.

And it has rarely been reported in two cases with fine needle aspiration.

Honestly, the true risk is unknown because with many of these low grade salivary lesions, you really need 10 to 20 year follow up to determine the true incidence.

And most of these studies have not had anything close to that length of follow up.

Even though it, we do not know the true risk, it is thought to likely be low with modern needle biopsy techniques, other complications such as hematoma or infection are uncommon and generally self-limited.

One recent review article on parotid biopsy in 2016 in the World Journal of Radiology had this to say about ultrasound core biopsy.

That ultrasound guided core needle biopsy is likely to supplant FNA as the biopsy technique of choice, replicating what has happened or has occurred already in other areas of medicine such as breast practice.

Our Approach to Salivary Biopsy at the University of Oklahoma

So what is our approach to salivary biopsy at the University of Oklahoma?

We use sedation in select cases, particularly if there is a very painful lesion or a phobic patient.

We use 1% lidocaine with epinephrine in essentially all patients, so long as we are not immediately adjacent to the vagus, and we will infiltrate a small amount of lidocaine within the gland.

This is because it hurts the patient as the needle traverses the salivary glands.

It's different than the thyroid, which once you get the needle within the thyroid gland, the patient generally doesn't feel anything, but it hurts all the way through the needle trajectory in the salivary gland, which is one of the reasons why we choose a needle trajectory traversing as little normal salivary tissue as possible.

The main reason is to avoid the facial nerve to by trying not to traverse a long length of salivary tissue.

Our approach is to begin with fine needle aspiration in the large majority of cases, and we begin with a 25 gauge needle with capillary action, and we may add a larger needle or suction if we initially return a poor sample.

We have the luxury of having excellent cytopathology, and they're present at these biopsies and provide immediate assessment of adequacy in the likelihood of definitive diagnosis.

And based on the preliminary cytology, we may add core biopsy, additional passes for flow cytometry, collection for culture, et cetera.

Why Begin with Fine Needle Aspiration?

So why do we begin with fine needle aspiration biopsy?

There certainly are those who would advocate just doing the core biopsy in all cases.

And the literature would certainly support that as a viable approach.

We feel that aspiration will make the diagnosis in a large number of cases.

And since we have good cytopathology support, that allows us to not have to do a core biopsy in many cases, which at least in theory, reduces the risk of complication and reduces the cost of the procedure.

Additionally, the preliminary interpretation allows us to determine if we need to take special passes for flow cytometry culture and other special tests.

Core Biopsy Technique

So what do we do with core biopsy if needed?

We use 18 gauge semi-automated adjustable side throw adjustable throw side cut needles, such as the Bard Mission or the Temno evolution.

And there are other devices similar devices available.

No incision is necessary in most patients.

Usually, single needle technique is performed, although occasionally coaxial technique is used in larger lesions.

We manually deploy the inner portion of the needle within the lesion and confirm the safe location prior to activating spring loaded outer cutting portion of the needle.

And here's how this is done.

Here you can see the tip of the needle placed at the margin of the lesion.

We then deploy the inner portion, and confirm that it is completely within the targeted lesion before activating the spring loading cutting portion.

And here is a video that shows the same thing, deploying the inner portion, confirming that it is completely within the lesion and then firing the outer portion.

And the thinking here is that we're trying not to take any portion of salivary tissue with the cutting device, only take the neoplasm or tumor.

And the rationale behind that is that benign lesions ought to push the facial nerve and salivary tissue away.

And if a facial nerve is engulfed within one of these lesions, then it is most likely doomed anyway.

The prior example was using a one centimeter throw.

This is a very large infiltrating lesion, as you can see here, which proved to be metastatic skin squamous cell carcinoma.

And since it was a very large lesion, we used a two centimeter throw to acquire an even larger piece of tissue.

Another example of a biopsy was this cystic lesion with a small solid enhancing mass seen on MRI.

Initial FNA was performed, of course, targeting the solid portion of the lesion.

This yielded some suspicious cells that were not diagnostic.

And we proceeded with a core biopsy.

And here you can see the cutting trough that is positioned within the solid portion.

And we did get a nice piece of this that allowed a confident diagnosis of mucoepidermoid carcinoma allowing for surgical planning for this patient.

Review of Our Cases

We have reviewed our approach of fine aspiration with core biopsy if needed.

And in a three year period, we had 135 procedures at our institution, 120 parotid, 15 submandibular.

You can see that we actually ended up only doing about 29 core biopsies, and we had a 90% diagnostic pathology.

And in the 41 cases that subsequently had surgery, we had a hundred percent sensitivity for malignancy, 92% specificity for malignancy, and we had no nerve injury or other major complication.

And some of the non-diagnostic pathology occurred in very small lesions that were questionable as to whether they were actually true lesions and neoplasms.

And on follow up, so far there have been no findings to suggest any false negative.

However, in all honesty, you really need 10 plus years for some of these lesions to be absolutely sure.

So we feel that this approach of fine needle aspiration with selective core biopsy is a viable approach.

Although the literature also would certainly support a approach where essentially all lesions are just sampled with core biopsy.

Approach to Deep Lobe Parotid Lesions

I want to briefly discuss approach to deep lobe parotid lesions at the end of this discussion.

Because they do require special approach and certainly are associated with greater anxiety among the proceduralists.

Fortunately, they're fairly uncommon, and in our institution, they very commonly come to multidisciplinary tumor board discussion, sometimes even before biopsy to confirm that this really is something that we need to do a needle biopsy on.

And MRI imaging is of use in a lot of these.

One of the reasons is that ultrasound imaging may be limited due to sound attenuation of the parotid tissue.

It is just difficult to see the very deepest aspects of the parotid gland.

Also, MR imaging is the modality of choice to look for perineural spread of tumor.

So what are the approaches?

One approach is a transparotid approach, where the needle goes straight through the parotid and crosses the plane of the facial nerve in order to enter the lesion.

And this is feasible with deep lobe lesions that are relatively superficial near the retromandibular vein.

Another approach is a posterior inferior approach, which is useful for posterior deep lesions, and then for very deep and particularly anterior superior lesions that are very medial.

A CT guided transfacial approach is also useful, and I'm going show you examples of all three approaches.

This is the large deep lobe lesion that I showed earlier in the talk.

That was a pleomorphic adenoma.

This is a very superficial lesion, and we just didn't it.

It's superficial, however it is in the deep lobe.

And we felt that really the most feasible way to come into this was a trans parotid approach.

And so this needle does cross the plane of the facial nerve as it enters the mass.

This lesion, on the other hand, was very inferior, and very posterior in the right parotid deep lobe.

And for this, we were able to do a posterior approach.

Here, the lesion is on CT, and here is an example of our needle approach coming from very posterior inferior approach and really barely even traversing any of the posterior inferior most aspect of the parotid gland.

And on CT. You can see our needle approach coming between the superior portion of the sternocleidomastoid muscle, and the posterior belly of the digastric muscle.

And as long as you come from a very inferior approach, this approach generally avoids the course of the facial nerve.

That being said, very superiorly, the facial nerve is closely related to the posterior belly of the digastric muscle.

The final approach that can be considered for a deep lobe lesion is a transoral approach, which requires CT guidance.

You can see this very medial and anterior lesion that is related to the deep lobe of the parotid in this patient.

And for this lesion, a CT guided transfacial approach was selected, because the trans parotid approach would be very difficult and a posterior approach was just not considered feasible.

Summary

So, in summary, a preoperative diagnosis of salivary neoplasms assists in planning therapy and counseling patients.

FNA of salivary masses is well established and is safe, but is limited by institutional variability, frequent non-diagnostic specimens, and low sensitivity for malignancy.

Ultrasound guided core biopsy of salivary masses is safe, when performed well with ultrasound guidance and significantly improves diagnostic yield and sensitivity for malignancy.

And I thank you for your attention.