The Plunging Ranula: Pathophysiology & Workup

[Ashley Agan MD]
Yes. It just occurred to me that we jumped into the patient presentation before we talked about what is a ranula. You talked about your spiel to patients about: What is a ranula?, How does it plunge? Can you just tell us what your spiel sounds like?

[Rohan Walvekar MD]
Yes, absolutely. It's really difficult to describe to patients and so this is how I usually tell my patients about ranulas. I tell them that the sublingual gland is this small gland that contributes to less than 1% of saliva, but then, when it gets obstructed, or it gets injured for whatever reason, it can really be troublesome. I talk to them about it being tucked between the mandible on one side and the mandible is trying to elbow it in.

Then the other side is the muscles of the tongue that are really sandwiching this gland in the middle. When the glands gets obstructed, or it gets injured, it starts leaking saliva because it has nowhere to go. Saliva leaks out of this gland, because it's overcapacity, and now it's flowing into the floor of the mouth. I tell patients that saliva in its normal space in the mouth, in the digestive system, is very helpful, but outside of that, and we know that from our laryngectomy, fistulas, and things like that, it's very irritant.

I graphically tell them that if I take a syringe, fill it with saliva, and inject it into my muscles, what it's going to do is going to create an intense reaction. When saliva leaks out from the sublingual gland, the body tries to create a reaction around it, almost trying to shepherd it into trying to stop the saliva from going to different places, and that what that looks like is a pseudocyst. Basically, a wall of inflammatory cells that really don't have any integrity, but it's just a way for them to curb that infection.

If that's limited to the floor of the mouth, then you see a cyst in the floor of the mouth, but at some point in time, this is just a free-flowing water, it's like a leaking faucet and sometimes the fluid will find weaknesses in the floor to be able to escape into the neck. These tend to be the neurovascular ports in the mylohyoid muscle. You actually see these weaknesses, or these areas of dehiscence while you do level one neck dissection.

If you really pay careful attention to your level one neck dissection, as you take this fibrofatty packet of tissue out of level one, you'll see a lot of vasculature over the mylohyoid muscles. Guess what, that's exactly where the saliva is going to flow out of and come into the neck. I talk to them about that and say that once it's in the neck, it forms this plunging ranula, but the source is that leaking faucet in the floor of the mouth, which is the sublingual gland. I don't know if that's helpful.

[Gopi Shah MD]
Moving on to our patient that's presenting with the ranula, what does your physical exam look like? What are you seeing and what are you looking for?

[Rohan Walvekar MD]
Honestly, the physical examination is very minimalistic. The main components I'm looking for is I examine the floor of the mouth for the patency of the submandibular duct. One is, can I visualize the papilla? Is it working? Because those are important things. If I do want to cannulate the duct for the procedure to maybe stent it so that I know where the duct is, I know that it's not going to be an issue or whether it's working or not. I can counsel the patients accordingly.

The second thing is obviously do a good bimanual palpation. You can get good elimination and examine the floor of the mouth. The best feeling is when you see that the ranula or a blue translucent thing in the floor of the mouth you know that your diagnosis is pretty much spot on. Sometimes you'll just look at the floor of the mouth and it'll appear normal and then what you want to do is do a comparative examination. Examine the normal side and see what the sublingual gland feels like, then examine the abnormal side and see if you feel it's slightly more bulky. That can give you a little bit of a clue as to whether this is truly a sublingual gland in origin. Then, of course, you bi-manually examine it.

If you have the ability to do an ultrasound in the office, that can be tremendously helpful. No harm in putting an ultrasound in the neck and just getting a sense of is this fluid collection around the submandibular gland, is the submandibular gland involved, or no. It's very difficult to sometimes see the sublingual gland in these settings because there's a lot of fluid around it but at least if you can examine the architecture of the submandibular gland, you'll know that it's not like a submandibular gland cyst. It's a combination of things.

I have an ultrasound in my office that I use pretty routinely for situations like this. I would definitely encourage you guys to-- at least whoever is listening or listeners to this podcast, to invest some time in learning how to do ultrasound of the head and neck.

[Gopi Shah MD]

Do you do an ultrasound even for anybody that has a intraoral component in the neck component or is it part of your neck mass workup anyways? If you have an intraoral component and you can see the blue and that clinical picture fits which you're thinking is that enough or do you feel ultrasound is something that you always do as an intermediary step?

[Rohan Walvekar MD]

No, I don't believe in doing things “just because you have to do them.” I focus my examination and interventions just to give me enough information to make a decision. If I am pretty confident that this is a plunging ranula, the ultrasound is not going to help me make that decision. I try to keep it as practical as possible.