Shreyaskumar R. Patel, MD: What are the risks of local recurrence? The literature mentions a wide range, but what’s your experience? Is it more common intraarticular or extraarticular? If you can walk us through that thought process, that will help.

John A. Abraham, MD: The recurrence rates are high, definitely higher for diffuse disease than localized disease, and the studies are a little bit all over the place in terms of what the exact numbers are. Part of that is because if you’re looking at different joints, we have different ability to achieve an adequate resection in different areas. We also think there is a spectrum of aggressiveness. When you lump those together in different studies, you’re going to come up with all these different numbers.

Surgical technique matters. Arthroscopic resection for diffuse disease is probably not a good idea based on everything we know from current studies, but the question comes up as to whether it is a good idea for localized disease. Dr Kim brought up a very good point that when you’re performing an arthroscopic resection, many times what that means is shaving the tumor down. We know based on the mechanism of how this works that there is a paracrine loop where 1 tumor cell is sending out a signal that is then recruiting cells into the normal synovium. So shaving that down and spreading that tissue everywhere is probably not a great idea. It has been borne out somewhat in the studies.

Initial studies did seem to suggest that for localized disease, arthroscopic resection and open resection were about the same. But as larger studies come out now with registry data and some international study groups for TGCT [tenosynovial giant cell tumor], the data from those studies, which include much higher numbers, do suggest that even for localized disease an open resection is better, at least in univariate analysis.

Even for localized disease, if the surgical resection is not particularly morbid, for instance, in most of the locations of the knee you can do what’s called a mini-arthrotomy, and make a very small opening and get to the lesion and remove it. That has a very minimal change in functional recovery versus an arthroscopic procedure. For those patients, I will perform a mini-arthrotomy. On the other hand, if it’s something like posterior disease or something that’s very difficult to get to, where an extensive dissection is needed, then I may turn to my arthroscopic colleagues and ask, “Is this a lesion you can get to?” Many times, those are areas that they can’t get to with a scope, so you may have to plan out the surgical approach differently.

Shreyaskumar R. Patel, MD: How often do you see a rapidly progressive course of the PVNS [pigmented villonodular synovitis]? You’re following the patient let’s say every 6 months to a year. Do you have to then start following them every 3 months? What fraction of the patients will have what you would label as rapid growth for this disease entity?

John A. Abraham, MD: It’s interesting, because I think there is a spectrum of disease, even within the category of diffuse disease. There are some patients who have diffuse disease where you perform a resection, and you never see them again and they have no problems. They are the minority, but that definitely exists. Then there are some patients who seem to have very aggressive disease and you can get a sense of that right from the beginning, because when they present the disease is much more extensive, with extraarticular and intraarticular components, or is much bulkier disease. They’ve already presented with erosions in the bone and local structures.

I would say—this is coming mostly from knee experience—the majority of people will fall in that category where you perform the resection and there’s a 40% to 60% chance that over the next 2 years or so, we’ll see a recurrence. Then there’s that 15% of the remaining patients who fall on either end of the spectrum, where you perform the resection and never see it again, or you perform the resection and 3 months later, you may already see disease coming back. That’s the minority, but it does exist. It makes me feel that even for diffuse TGCT, there’s still a pretty extensive spectrum. I wonder if there could be some molecular basis to that, but that remains to be seen.

Robert G. Maki, MD, PhD: Dr Abraham, does the synovium regrow after you do a synovectomy in the knee?

John A. Abraham, MD: That’s a good question, and I don’t know that we really know the answer. In general, we think that no, it doesn’t grow back. You may get some scarring and you may get some replacement tissue in that area. Usually its fatty tissue, if you end up going back into that area. We think generally, it doesn’t really regrow completely the way it was previously.

One of the questions we get commonly from patients is, “You’re going to cut out my synovium? Don’t I need that? I never knew I had it, but don’t I need it?” The synovium does have function in normal joints, and it helps lubricate the joint and it provides nutrients and there’s oxygen exchange. Things like that happen for the joint through the synovium, but for all those functions in a normal joint you only need a small percentage of your actual synovium, maybe 10% of the synovium of your knee. It’s much more efficient with a knee full of synovium, but for that knee to function normally over time, you probably need 5% or 10%. Looking at most of these joints, we can’t get out 100% anyway, so when we do a “complete resection,” we’re talking about taking out 85% of the synovium at best. That’s in the knee. And other joints like the hip, without a surgical dislocation, there’s no way you could get 85% of the synovium out. The remaining synovium is usually adequate and probably doesn’t regrow. We may see some areas of regrowth, but we don’t see long-term problems from the synovectomy alone.

Shreyaskumar R. Patel, MD: Dr Kim, do you have any additional thoughts on the multiply recurrent, multiply operated, diffuse-variant, difficult case? Is there anything else to add?

Tae Won B. Kim, MD: I think in those patients you have to not jump into surgery. I think you’ve got to pump the brakes on that decision and start to go back to your tumor board. Go back to everybody and discuss it as a group. Institutions in areas that have seen a lot of this, those channels have already been created treating other sarcoma patients, and I think that’s where the multifocal recurrent patients need to be triaged and evaluated. I think without that, as an orthopedic surgeon you think, “Yes, I want to go in and do something. I want to take this thing out.” But you would ultimately end up hurting patients if you don’t take a more multidisciplinary approach to that.

Transcript Edited for ClaritySupported by an unrestricted educational grant from Daiichi Sankyo.