Salivary Gland Tumors

00:01 Welcome. In this talk, we're going to cover salivary gland tumors.

00:05 And fortunately, the vast majority of these are going to be benign, but there are some malignant variants. Getting to the point about benign versus malignant.

00:16 The majority, the vast majority of tumors of the salivary glands are of the benign category.

00:22 So they will fall under pleomorphic adenoma and Warthin tumors that we'll revisit in a moment and look at the way that they appear under the microscope.

00:31 There are occasional malignant tumors, so about 15% of the salivary gland tumors are going to be malignant and mucoepidermoid carcinoma is at the top of that list.

00:43 There are also things that we're not going to be talking about which regard to tumors, apparent tumors of the salivary glands and that's inflammation.

00:51 So inflammation can cause swelling, edema, some increased redness, etc., and that's not something we're going to cover in this talk.

01:01 And we're also not going to cover lymphomas which will also occur within the salivary glands but are a different entity altogether.So let's start with pleomorphic adenomas.

01:12 Again, benign and the epidemiology of this is most common of the salivary gland tumors, more common in women with a peak incidence in middle age.

01:22 It's associated with prior radiation although it doesn't have to be caused by prior radiation and very, very rarely, there can be malignant transformation.

01:32 So in all cases, you will need to excise this and send it off to pathologists to see if there is a malignant component.

01:40 The pathology, and we're not going to turn you into pathologists but just to be aware of how these things look underneath the microscope.

01:48 So of the pleomorphic adenomas, they're called pleomorphic because they're a combination of elements.

01:53 There are myoepithelial cells that surround apparent glands as you see there on the left.

01:59 There are also epithelial cells in sheets as you see on the right as well as a very loose myxomatous stroma and that can sometimes even contain cartilage or bone.

02:10 So these are the elements of a benign pleomorphic adenoma.

02:14 sorry, this is usually a slow-growing, painless, and mobile mass.

02:19 So it's not fixed to the underlying structures.

02:22 The management is surgical resection and the prognosis is very good because in the vast majority of cases, this is a benign tumor.

02:31 Let's move on to the second category of benign tumors which are called Warthin tumors.

02:35 The epidemiology of these is a little different.

02:39 So this is a second most common of the salivary tumors.

02:42 Again, it's benign. It is associated with tobacco smoking whereas the pleomorphic adenoma was not.

02:48 It's also frequently bilateral, so about 10% of the time and in an individual gland, there may be multiple foci.

02:57 It mainly involves the parotid gland as opposed to the sublingual or the submandibular glands.

03:04 The pathology is - looks a little bit different.

03:07 So on the left-hand side, we're seeing some of the imaging with a large mass involving the parotid.

03:12 But on the right hand side, we're seeing the histology.

03:16 And histology shows a palisading, that means a stacked rim of benign epithelium that surrounds a central cystic area, that's the cleared out space.

03:26 And there are frequently multiple germinal centers within it.

03:30 So it has a very characteristic look to it. It looks different than the pleomorphic adenoma which had multiple different elements.

03:36 The management, very similar except that it's involving more commonly the parotid gland and coming through the parotid gland is going to be a branch, an important branch of the facial nerve.

03:47 So for you future surgeons out there, you need to cut this out very gently to preserve that facial nerve so that people can smile and grit their teeth.

03:57 So what's shown here is actually a very interesting specimen and part of the reason that we send all these out for pathology even when we know that we - they are benign, this is a tumor, this is a mass that was in a patient's parotid.

04:09 It had both a Warthin's tumor, identified here as WT.

04:14 But it also had incidentally adjacent to it, mucoepidermoid carcinoma.

04:20 And that's what we're going to see on the next - on the next part of this talk is the malignant variants of salivary gland tumors.

04:29 So mucoepidermoid carcinoma, the malignant variant or one of the more common malignant variants of salivary gland tumors.

04:38 Epidemiology on this is that this is the most common.

04:41 There are a couple other types that we're not going to go into because they're relatively infrequent.

04:45 It's only about 15% of all salivary tumors are the mucoepidermoid carcinomas.

04:52 And again, like a Warthin's tumor, occur more frequently in the parotid.

04:58 These are interestingly enough frequently almost half of cases are associated with a chromosomal translocation that creates a fusion protein between the CRTC1 and MAML2 proteins and that affects intracellular signaling so that you get uncontrolled proliferation of the cells.

05:19 The pathology is a combination of a mucinous component, so on the left-hand side, the kind of grey pink acellular material is mucin and then, there are epithelial squamous cells and it's always a combination of those two.

05:38 On the right, we see more of the epithelial cells that have a very cleared out cytoplasm with relatively less of the mucous component.

05:47 The prognosis overall is very much dependent on the histologic grade, so whether it's very poorly differentiated or very well differentiated.

05:55 I'm not going to abuse you with that kind of information.

06:00 Don't expect that you would be able to recognize that on a slide.

06:03 That's why we have pathologists like me who will look at them down a microscope.

06:08 But depending on that degree of differentiation, the histologic grade, survival can be everywhere from 50% in five years to 90% for very well differentiated tumors.

06:18 And with that, we close with our discussion of salivary gland tumors.